Keep him!!!!
Kensai's as they get higher, get such a low THACO that they don't get hurt as much. At the beginning, what you need to do is use a tank(Minsc) and send him up first. While he's taking the hits, have your Kensai slash em up. Kensai;s are, IMHO, the best fighters in the game in terms of offensively.
Of course, I'm sorta biased, seeing as I love my lvl 10 Elven Kensai.
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Lil' Angel 
Sword Saint and Enchantress of the HADB Clan
The Lady Lioness of Castle Kerhelm
Waitress at Cloudy's Cafe and the Promised Land
Official Restrainer of Table Dancers
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Emerald Dragoness of DOTW