Bagpuss
Legend
Overall, I dig it. My one real worry is the Rod of Deadly Casting. Exploding 10s, even on crit damage, could get too ugly too fast.
It compares with a Vorpal Sword, but that is ONLY a level 30 +6 enhancement item, the exploding isn't available at lower level. But it also applies to any die rolled with that weapon, not just on a critical.
I'm not sure about exploding dice at lower levels. It's very "swingy" and I thought 4th Ed was about removing those sort of factors. That make it hard to balance an encounter.