My last character was a NE Human Kensai, dualled to Mage at level 12.
Strengths: Grandmastery in Katanas, Mastery in 2-Weapon Style, Stoneskin, Haste, Contingency, dual wielding Celestial Fury and Zerth Blade. This combo makes a very fast, very efficient killer. With Stoneskin and Haste, my Kensai/Mage was almost unstoppable. He could shread most enemies before they even got an attack off.
Weaknesses: After dualing over to Mage, you get a good amount of time where your character can seriously affect the performance of your party due to the loss of Kensai abilities and the fact that you are only 1st level. (Unless you planned ahead and brought along the right NPCs...which I did...) Once the character has regained his or her Kensai abilities, all bets are off...
Glycerine