A few levels of Crusader would do some really good stuff for you:
1) They have stances that mesh really unbelievably well with knight abilities.
2) There are strikes to increase the damage of the weapon you're wielding in one hand.
3) There are nifty protect-others counters that require a shield.
4) They have good Fort saves, and you can add Charisma to Will saves.
There's more too, but those are the biggies.
-blarg