Does he really land on the same point, or does it only appear that way until the next turn starts, at which point he appears where he should have been? I've seen the latter bug.
Given some recent statements that +1 [Ability] gear will be a lot more useful, I think being able to buy and use spells you can only get wearing +1 gear is intentional, but you're right that you should not be able to use those spells after you lose the bonus.
