CRIT type would be an assassin that deals critical damage, thus depending on LUK.
For CRIT type I would suggest going katar. Get yourself a three slotted Jur and equip 3 soldier skeleton cards.
Using daggers on a CRIT sin is useless since daggers are made for double attack, but you won't deal double damage when hitting crits.
There is also the Dex-Katar build, this allows maximum use of SonicBlow and Grimtooth, or in other words, Mobbing and killing Mobs Quickly and Efficently.
While Critical is for less advanced Click-Killing.
Dex 60 allows you to hit majority of the mobs in the game w/ SonicBlow and Grimtooth.