Re: Finding something Hero System can't model...
Maybe a magic wand that does more damage if the wielder's INT or EGO is high. Or a Nimble Blade, where DEX adds. Compelling an extradimensional being to attack, where PRE influences how hard they hit. How about a power that causes great (but transient) pain in the wielder, so hardier individuals (high CON or BODY) can withstand more?
The topic came up as I was mining 4e D&D for ideas. There, all characteristics can add to damage (or other effects). Hero lacks that flexibility.