As I've said though, why does it have to be explained IN THE FICTION, it is not a constraint of the character, it is a constraint on the PLAYER. I have a certain number of 'plot coupons' which are my 4e character powers. Some are just 'stock in trade' and don't need to be regulated (Twin Strike). Some are more bad-ass moves and generally the situation only arises where I try to pull them off once per fight (Precise Assault), and then there's the really bad assed one that I am able to expend once a day (Split the Tree). That's just the 'rules of the game', it isn't any sort of anything that is inherent to the character. Technically he could Split the Tree 42 times a day under perfect ideal circumstances, they just never come up (and there are, to be fair, ways to get recharges on stuff too, though they are pretty hard to get, or else require a rare consumable, etc. for obvious reasons). The point being, lots of ink was spilled on this for ages and it really never made sense.