So today i did check a talents and found something interesting about Talents which gives you boost from armor you wearing.
Heavy armor:
1) from Templar tree Stouthearted (increase bonus defense received from Heavy armor items by 2%/4%/6%)
2)Warrior tree Battle Hardened (for each heavy armor piece equipped you gain and extra 1%/2%/3% of melee attack power)
Light armor:
3) Mage tree Mental Agility (increase your spell haste 1%/2%/3% for each piece of light armor equipped)
4) Prophet tree Prophecy (increases your mana regeneration 2%/4%/6% for each piece light armor equipped)
Medium armor:
5) Assassin tree Ambidextrous (increases critical chance whit one handed melee weapons by 1%/2% for each medium armor piece equipped)
6) Ranger tree Dexterous (increases your ranger and melee haste by 0,5%/1%/1,5%/2% for each medium armor piece equipped)
So after this we can see that Heavy and Light armor boost give something for both classes but medium armor only Assassin gets something from both talents, but ranger gets only from his tree. So i would suggest that Assassin tree talent Ambidextrous now would be like this - increases critical chance whit one handed melee weapons and bow, crossbows by 1%/2% for each medium armor piece equipped