For PVE which weapon are good for Knight? 

+7 Two-Handed Sword of Pretender King
+7 Axe of Raging Wind 
Ancient Sword 

Wind Axe and Ori dagger are all that you need until you get CB.

Can you tell me why these 2 are better? 

ori dagger is best pve weapon (single target) untill you get Fid

why? because of the fast swing speed, high avg dmg, extra dmg vs undead and unbreakable.

wind axe for leveling because of the aoe, can use it in dk morph, unbreakable, higher dmg than ice spear (results may vary tho, some people say ice spear is better because it has faster swing which means you proc more often, it's also one handed so early it may be better..most prefer the wind axe tho)

Thanks for the information. I just make a +7 ori dagger. Next one I’m going to get are wind axe. 

Currently lv48 hunting Giran prison 

what is CB?

CB is Counter Barrier, Knight Skill that counterattacks when attacked.