The kit is normally less effective than a normal Fighter, since low AC means he gets clobbered. Once he activates the Offensive Spin he becomes a murder machine.
Re-writing the Offensive Spin sounds like a good idea for when I actually get to work on the mod with the kit. Perhaps it would start without an extra attack, then give a 1/2 additional attack and finally add one full attack as the character nears 10th level. Conversely, I could make the Defensive Spin more front-loaded, since an increase in AC by 1 or 3 isn't worth being rooted in the spot. Perhaps it could start at 3 and cap at 10 by level 7? It does last only 24 seconds, so maybe it wouldn't be overpowered.
Alternately, or in addition to it, I could give it chainmail proficiency. Chainmail doesn't normally see much use, since the classes who can wear it can wear heavier armor as well. It could make the kit too strong, but it's an idea.