Iron Fortress: When defending (using a shield to block attacks), it becomes impossible for your avatar to be launched by a powerful attack (prerequisite: shield skill x(I have no clue about how high I should make the skill))
Throwing Apprentice (could be expanded at higher levels): improves the accuracy and range of sword skills that involve throwing a weapon
Wall Runner: Vastly improves the traction that shoes have on any vertical object, allowing for limited vertical/horizontal wall running (prerequisite: Agility 400) (could expand into High Level that increases the traction even more, allowing Naruto style wall-runs)
Like a Feather: Nullifies all falling damage (prerequisite: Agility 550)
Unstoppable: Multiplies max lifting capacity/stopping power by a factor of three (prerequisite: Strength 1000) (I'm thinking, this plus the strength modifier would allow the player to perform feats like catching the punch of a boss-level monster with their hands)
Jack of All Trades--Ultimate: In terms of equipping weapons, the players strength and agility are seen as 500 points higher than it actually is (this would allow a player to equip weapons that would usually be outside their character build) (prerequisite: all previous Jack of All Trade skills)
These are, of course, only examples. The actual perks could be anything. What do you guys think?