Are their any changes from standard in the basic sunder usage? I didn't see any obvious additions other than allowing ranged attacks to sunder, although I suspect you've also removed some other limitations.
Reread it and noticed the bit about an extra attack if you destroy the item. I'd shift that to the Improved Sunder feat, much like Improved Trip's bonus attack.
I'd expect the anti-magic only disable-without-destroying option to be in Dweomercleave, which is the feat about sundering magic, rather than Improved Sunder, which is just about breaking things in general. Since it's in the basic feat, which otherwise has nothing to do with magic specifically, it seems weird, especially since you don't have the option to sunder without breaking for nonmagical objects. It just doesn't fit thematically in there, even more so since you're cramming in the repairing parts as well. It would be rather more complicated, but I'd love to see a nonlethal damage equivalent for objects in general (and possibly constructs, too) that makes them broken but repairable (as opposed to totally destroyed). That would let pseudo-breaking things just be a general sort of thing that the sunder master also becomes really good at.
Let me see if I'm getting this straight with Boneshatter. You sunder an opponent's item and break it (since you're moderately optimized and deal good damage per hit, this is reasonably reliable). Sundering gives you a replacement attack against the item's wielder. That attack hits. Then you get a second attack. In essence, you have broken one of your opponent's items, and doubled your attack.
Dweomercleave doesn't need the lines about spells being unhealable. The fact that there aren't any effects that do so already makes that the case. Because spells don't have hp normally. Speaking of which, you should make it a general rule to calculate a spell's hp, rather than having it be defined by a specific feat. That way, you won't run into conflicts if another effect defines a spell's hp (possibly equally generically). Although as far as I'm concerned, spells having hp is weird, probably unnecessary, potentially adds extra dollops of bookkeeping, and is weird. There should be a better solution.
Attacking the caster makes little sense with Dweomercleave. I'd expect it to let you attack the subject of the spell if it was a spell affecting a creature or object, but there's no correlation between where the caster and where the spell are. Even if they're both in melee with you, they could be on opposite sides of you. I'd only expect it to let you attack the caster if you were using a readied action to disrupt the casting. Also, why can you only ready to sunder instantaneous spells? It makes even less sense once you consider that even if you know your opponent is going to cast a spell and thus you ready against it, they're not necessarily going to cast an instantaneous one, and you as the big stupid fighter without Spellcraft ranks won't be able to figure it out until after the spell is finished casting anyways.
Blargh. It's late and I'm pretty sure that I'm misreading things. And miswriting things. And just missing things.