I actually stumbled on this while browsing elderly Reddit RPG design threads, and fell down a magical rabbit hole
I do wonder if having four depletable defences might prove a bit much in actual play but on a gut level it feels pretty manageable: I suppose it's really no different from, say, attribute damage in other systems, and it seems a pretty integral mechanic (in terms of someone being forced to sacrifice something even on a relative "miss", I love glancing blows/graze mechanics)
But put short, I'd love to play this and see if it's as good in practice as it is on the page! What a great system, and a solid setting to boot