Everytime i gained a level, my critical chance decreases despite me gaining 1 agility.
However, it slowly increases when i gained like half the xp bar..

why is this?
Same level, same equipment, no buffs.

I'm a warrior btw.

weapon same -.-"

you don't believe me?
Later i go home, i create new char, i show u level 1 and level 2 critical chance difference.

Press K when you are in the game, check out the weapon proficiency and other skill lvl bars.

Its your weapon skill la. You get 5 weapon skill per lvl.

Starting of a level, lets say its 50/55 for lvl 11.

As you hit more mobs when you lvl, the skill lvl will slowly rise up. 51/55, 52/55, 53/55,54/55/ and finally cap at 55/55.
Each weapon skill increases crit by 0.04% if im not mistaken.
Then you have to wait till next lvl for higher cap.

http://www.wowwiki.com/Formulas:Weapon_Skill