Personally here is my experience....
200 dex should be your minimum in Canta with 300+ beind the gold standard. I would rather hit someone for a non critting 400 than not hit them at all... 200 is a minimum.
450+ Luc should also be the minimum for a Canta archer while 500+ is preferable.
str isn't quite as important but any attack dmg is good because it will increase your crits. This should be the last stat you focus on though. Good atk dmg can be achieved from high enchants.
Also ele weaps are a must to get decent dmg output.
On a side note... full luc archers without dex are terrible. Most of Canta's regular fighters, archers, and rangers will be running with at least 200 dex with some pushing 400 dex. Plain and simple... no dex and u will not hit them very often while they will hit you every hit regardless if it crits.