best rings for daggers = fallen angel ring +6++, dragon ring +3 ( obviously ), Olympiad ring 30 days , god accessories rings, and with this new update coming, angel ring +6... u can use fallen angel ring + angel ring... angel ring is craftable, but u need atleast 8-9 days farming aether, to craft 1... ( crafted rings are not tradable )...
dex is good for daggers in same way for archers... increases crit chance of skills...
crit dmg increases your normal attack crit, and your skill dmg..
your skill crit dmg, increases your skill dmg and your skill crit...
imo dex is good for daggers not cuz half kill... but cuz increases blow land rate... and skill crit chance... so when your blow crit, it will increases all yours crit dmg + skill crit dmg bonuses, doing a lot of dmg...
when i was a dagger b4 fafurion, i always use dex, cuz human have way too low dex, and miss alot of blows...