Well I am not going to use the knight side to tank since the w/k elites are made for tanking and such. However I would like to use the knight side as DPS when needed since the elites are based on DPS
If you really want to Dps... Stick to w/k. I am not familiar with w/k elite skills but besides the ability to wear plate, I can't recall anything that is for tanking.
K/w only has the weapon mastery that is somehow related to dps. The rest... K/w is a tank. Higher dps than most other knights, but still a tank.