mighty/obliterating/almighty etc. melee attacks

You mean like a line of reasonably common shields that have cards that only block attacks of 11 damage or more? That would be pretty interesting...
But how would you reliably get them into the hands of the right people without spamming SP loot drops with them? Until we get a content expansion, I'd get pretty annoyed if something that was obviously PvP-only gear started dropping with any regularity while I was trying to enjoy my SP experience. I'd start to get annoyed that my loot's usefulness was being diluted with junk. In retrospect, this sounds like the sort of thing that's specifically only available for cheap at the PvP store.

 

I think you have to look at everything in terms of weakness. To me the weakness of double Bejeweled short Swords are that you have 4 left. This means you can't use things like Emperor's Plate or a decent shield. I like the idea of obliterating shields, but I also think that there just isn't enough weakness in some of the items that have obliterating things. The damage is another layer of strategy, though, so if Blue Manchu nerfs the obliterating line they don't have to nerf damage. They could just as easily add a drawback to the card, kind of like Massive Chop has, or perhaps something like what Violent Overswing has.

 

that's exactly what I was thinking