Let the speculations begin! Taken from: http://www.reddit.com/r/ffxiv/comments/1jj5is/august_1st_datamined_classjob_ability_changes/

Paladin:

Riot Blade Combo potency increased from 200 -> 230

Rage of Halone Combo potency increased from 240 -> 260

Sword Oath: Auto attack potency increased from 25 -> 50

Shield Swipe: Potency Increased from 170 -> 210

Awareness: Reduced oncoming crit chance increased from 15% - 25%

Shield Oath: Both oncoming damage reduction and outgoing damage reduction flatlined at 20%

Circle of Scorn: Base potency increased from 30 -> 100. DoT Potency now 30.

Monk:

-No longer has Gladiator as a sub-class.

-Now has Marauder as a sub-class.

Second Wind: Now scales off curing potency, which scales with attack power. Due to XIVDB basing ability tooltips off of level 50s, with Third Wind this has a 650 cure potency. Likely around ~400 potency without Third Wind.

Touch of Death DoT potency reduced from 40 -> 25.

Fist of Fire Damage increase reduced from 10% -> 5%

Mantra: Now applies to the Monk and an area directly around the Monk.

Howling Fist potency reduced from 190 -> 170. Recast reduced from 300s -> 60s.

Dragon Kick: Also reduces target's INT by 10%.

Warrior:

Maim: Combo Potency increased 180 -> 190. Damage bonus increased from 10% -> 20%

Mercy Stroke Potency reduced from 250 -> 200.

Defiance: "Damage dealt reduction" decreased from 35% -> 30%

Butcher's Block Combo Potency increased from 260 -> 280

Inner Beast Potency increased from 260 -> 300 -Changed to absorb 300% of damage dealt

Storm's Path Now also has a combo potency of 250. Absorption Shield buffed to 50% of damage dealt with no max hp cap up from 20% of damage dealt capped at 10% max hp.

Storms Eye Combo Potency Increased from 230 -> 270 Now also applies reduced healing on target by 50%

Dragoon:

-No longer has Archer as a sub-class.

-Pugilist has been added as a sub-class.

Keen Flurry: Parry rate increased from 20% -> 80%

Vorpal Thrust level reduced to 4

Keen Flurry Level increased to 6

Life Surge: Healing component reduced from 20% -> 10%

Jump: Potency increased from 180 -> 200. Recast reduced from 60s -> 40s.

Phlebotomize: DoT potency increased from 10 -> 20.

Power Surge: Recast reduced from 180s -> 90s.

Dragonfire Dive: Recast reduced from 300s -> 180s.

Exhilarate (trait): Additional TP gained from Invigorate increased from 450 -> 500.

Bard:

Hawk's Eye: Additionally Grants 15% DEX

Windbite: DoT Potency increased from 40 -> 45

Quelling Strikes Level lowered to 36.

Flaming Arrow level increased. Potency Increased from 25 -> 35

Enhanced Quicknock: Level reduced to 36.

River of Blood (trait): Level increased to 48. Chance of Bloodletter CD resetting due to DoT damage on Venombite and Windbite increased from 20% -> 50%. Still requires DoTs to crit.

Rain of Death: No longer increases damage taken on targets hit by 10%

White Mage:

Stone: THM removed from list of classes.

Cure: Potency increased from 300 -> 400. ACN/SMN/SCH added to list of available classes.

Cleric Stance: SCH added to the list of available classes. THM has been removed from the list of available classes.

Protect: ACN/SMN/SCH added to list of available classes.

Medica: Potency Increased from 250 -> 300.

Raise: ACN/SMN/SCH added to list of available classes.

Cure II: Potency Increased from 500 -> 650.

Stoneskin: ACN/SMN/SCH added to list of available classes.

Regen: Potency increased from 50 -> 150.

Shroud of Saints: Refresh Potency increased from 60 -> 80.

Cure III: Potency increased from 400 -> 550.

Medica II: Potency Decreased from 350 -> 200. -Regen potency increased from 50 -> 100.

Black Mage:

Thunder: ACN/SMN/SCH added to list of available classes.

Surecast: ACN/SMN/SCH added to list of available classes.

Blizzard II: Now grants Umbral Ice II.

Scathe: Potency increased from 100 -> 120 (With trait from 200 -> 240)

Fire II: Now grants Astral Fire II.

Thunder II: WHM removed from list of classes.

Swiftcast: ACN/SMN/SCH added to list of available classes.

Blizzard III: Potency Increased from 200 -> 220. Now grants Umbral Ice III.

Fire III: Potency Increased from 200 -> 220. Now grants Astral Fire III.

Arcanist:

-Sub classes are Conjurer and Thaumaturge.

(Lv1) Ruin: 80 potency. WHM, BLM, CNJ, THM

(Lv2) Bio: 40 Potency for 18s. WHM, BLM, CNJ, THM

(Lv4) Summon: Summons a caster/healer-type pet. (DEPENDS ON JOB EQUIPPED)

(Lv6) Aetherflow: Restores 20% of maximum MP.

(Lv8) Enhanced Aetherflow I: Grants 1 stack of Aetherflow when Aetherflow is cast.

(Lv8) Energy Drain: 150 Potency. If under the effect of Meta Ether absorbs 50% of damage as hp and restores MP.

(Lv10) Miasma: 20 initial potency. 35 potency for 24s. Disease: Reduces hp recovered by Cure spells by 50% and heavy+40% for 24s

(Lv12) Virus: Reduces target's STR/DEX by 15% for 10s. WHM, BLM, all classes.

(Lv14) Int boost 1: INT+2

(Lv15) (CLASS QUEST) Summon II: Summon a tank/support pet. (DEPENDING ON JOB)

(Lv16) Int boost 2: INT+4

(Lv18) Sustain Sacrifices 10% max hp to continuously restore 8% pet hp over 10s. Cannot execute if under 10% hp.

(Lv20) Enhanced Aetherflow II: Grants 2 stack of Aetherflow when Aetherflow is cast.

(Lv20) Enhanced Action Damage I: Appears to give +10% action damage bonus.

(Lv22) Ressurection: Raises a target in a weakened state.

(Lv24) (Trait) 20% chance on pet crit to give you 20% spell speed for 8s.

(Lv26) Bio II: 35 potency DoT for 30s.

(Lv28) Causes Virus to also reduce INT/MND by 15%.

(Lv30)(CLASS QUEST) Bane: Spreads Bio, Bio II, OR Miasma to all nearby targets for their remaining time. If Aetherflow effect is up, 15% chance for DoT durations to reset.

(Lv30)(SCHOLAR). Succor: Restores target hp. Potency of 300. Erects a barrier nullifying damage equal to the amount of hp restored. When heal crits, barried doubles.

(Lv30)(SUMMONER) Summon III: Summon an attacking pet.

(Lv32) Int boost III: INT+6

(Lv34) Eye For An Eye: Places barrier on target or pet for 30s. Anyone who strikes shielded target has a 20% chance to have their damage reduced by 10% for 20s. WHM, BLM, all classes.

(Lv35)(SCHOLAR) Succor II: Restores Hp in an area around the caster. Potency 150. Grants a shield to each member healed that nullifies damage equal to the cure.

(Lv35)(SUMMONER) Fester: Deals 100 potency on a target per DoT (Bio, Bio II, Miasma). Only self applied DoTs work and must be under Aetherflow effect. 10s CD.

(Lv36) Enhanced Energy Drain: Doubles MP gained from energy drain.

(Lv38) Ruin II: 80 potency. Blind for 10s.

(Lv40) Enhanced Aetherflow III: Grants 3 stack of Aetherflow when Aetherflow is cast.

(Lv40) Enhanced Action Damage II: Increases Action damage by 30%.

(Lv40)(SCHOLAR) Leeches: Removes a single detrimental effect on target. 1s cast time

(Lv40)(SUMMONER) Tri-Disaster: AoE Bind on target. 30 Potency.

(Lv42) Miasma II: 20 initial AoE potency around caster. 10 potency DoT for 15s. Disease.

(Lv44) Reduces Eye For An Eye CD to 120s.

(Lv45)(SCHOLAR) Sacred Soil: Creates an area where everyone inside takes 10% less damage. Duration 15s. 20% Next Succor II will cost no MP. Can only proc under Aetherflow.

(Lv45)(SUMMONER) Spur: Increases a pet's physical/magical atk power by 40%.

(Lv46) Rouse: Increases cure magic potency and damage deal by pet by 40%. When roused, pets are immune to all detrimental effects.

(Lv48) Reduces CD of Rouse to 60s.

(Lv50) Shadow Flare: Placed AoE of 25 potency for 30. 5% chance of inflicting Slow to targets.

(Lv50)(SCHOLAR) Lustrate: Restores 20% of Target's maximum hp. 1s GCD. Only available under Aetherflow.

(Lv50)(SUMMONER) Enkindle: Allows pet to use its signature attack. 5m Recast.

Arcanist Pet Abilities

Emerald Carbuncle

-Gust: 90 potency wind damage

-Backdraft: 80 wind potency knockback

-Downburst: AoE 80 potency

-Shining Emerald: Extends Masters DoT effects by 15s.

Topaz Carbuncle

-Shining Topaz: AoE 70 potency. Increased Enmity.

-Gouge: Single target 70 potency increased enmity.

-Curl: Decreased damage taken on pet by 20%.

-Storm: Delivers an attack for 60 potency that stuns.

Scholar Pet Abilities

Fairy (2 forms, support and healer)

-Whispering Dawn: AoE regen around pet. Potency 100 for 21s. 30s recast.

-Embrace (both forms): 300 potency cure.

-Silent Dawn: Silences for 1s. 40s recast.

-Fey Glow: Increases Spell speed around pet by 30% for 30s. 60s Recast. Cant use at same time as Fey Light.

-Fey Covenant: Increases Magic Defense around fairy by 20% for 20s. Recast 2m

-Fey Light: Increases skill speed around pet by 30% for 30s. 60s Recast. Cant use at same time as Fey Glow.

-Fey Illumination: Increases Cure magic potency around pet by 20% for 20s. Recast 2m.

Summoner Pet Abilities

Titan Egi

-Mountain Buster: 70 AoE potency around Titan. Increases Enmity. 15s Recast

-Rock Buster: Single Target 85 Potency. Increases Enmity.

-Earthen Ward: Decreases damage suffered by pet by 20% for 20s. 2m recast.

-Landslide: 70 potency stun. 40s Recast.

-Enkindle: Earthern Fury - AoE 200 potency. Additional effect: Razed Earth.

Ifrit Egi

-Crimson Cyclone: 105 potency stun. 40s CD

-Burning Strike (?): Single target attack potency of 120.

-Radiant Shield: 50 potency damage everytime Ifrit is attacked.

-Flaming Crush: AoE 105 potency. 30s Recast.

-Enkindle: Inferno - Conal 200 damage. 20 Potency fire DoT for 15s.

Garuda Egi

-Wind Blade: Wind Potency of 100.

-Aerial Slash: Deals AoE wind dmg around target. 90 Potency.

-Contagion: Extends master's DoTs by 15s.

-Shockwave: 90 dmg knockback.

-Enkindle: Aerial Blast - 250 AoE dmg.

Crafting Classes:

-Master's Mend II level reduced from 28 -> 25.

-All Brands as well as Flawless Synthesis and Steady Hand II have had their level increased from 25 -> 37.

-Standard Synthesis level decreased from 33 -> 31.

-Advanced Touch level increased from 37 -> 43.

-All previously level 43 crafting specific abilities (Careful Synthesis II, Byregot's Blessing, etc.) have had their level increased from 43 -> 50.

Gathering Classes:

Miner:

Deep Vigor level increased from 23 -> 25.

NEW ABILITY: Truth of Mountains - Further survey the landscape to uncover unspoiled mineral deposits and rocky outcrops.

Toil of the Mountaineer level increased from 43 -> 50

Botanist:

Brunt Force level increased from 23 -> 25.

NEW ABILITY: Truth of Forests - Further survey the landscape to uncover unspoiled mature trees and lush vegetation.

Toil of the Pioneer level increased from 43 -> 50.

Fisher:

(Lv1) Quit: Abandon fishing attempt and reel in line.

(Lv1) Hook: Attempt to hook the fish nibbling on the bait.

(Lv1) Cast: Cast your line and begin fishing.

(Lv1) Bait: Select the bait to apply to your line.

(Lv8) Stealth: Conceal yourself and tread quietly, reducing movement speed, but enabling you to avoid enemies level 20 and below.

(Lv15) Ocean Whisperer: It is possible to fishing to discover the best-kept secret up to Level 15.

(Lv18) Enhanced Stealth: Able to avoid detection on monsters up to level 30 while stealthed.

(Lv25) Mooch: Use the fish already hooked to your line to attract even larger prey.

(Lv28) Enhanced Stealth II: Able to avoid detection on monsters up to level 40 while stealthed.

(Lv35) Ocean Whisperer II: It is possible to fishing to discover the best-kept secret up to level 35.

(Lv35) Sand Sea Fishing: It is to run as a cast fishing the sand sea.

(Lv38) Enhanced Stelath III: Able to avoid detection on monsters up to level 50 while stealthed.

(Lv40) Enhanced Mooch: The feed on fish caught in fishing swim, it is able to perform casting.

(Lv45) Sea of Clouds Fishing: It is to run as a cast fishing the sea of ​​clouds.

(lv50) Ocean Whisperer III: It is possible to fishing to discover the best-kept secret up to level 50.