I was dicking around in a bot game as TF stacking gunblades. (I mean he's a cowboy - gotta have two greaves and 4 guns, right?). Anyway, on my third gunblade, I noticed that I wasn't really vamping as much as I should have been. I went to check my stats and life steal and spell vamp were both at 60%, when it should be 60% and 75%, respectively.

The game ended before I could get my fourth, so it may just be that the new gunblade only says it gives 25% vamp while only giving 20%, or it may actually be capping at 60%.

EDIT It is not in fact capped, the gunblade was never actually updated.