“ Held in a lead sheath the blade of this sword is tipped with uranium and any wound from it, even a tiny one, will go cancerous, although the effects may not show up for months or even years.”
“ Thrown enchanted skulls make great necromantic 'grenades' releasing blasts of negative energy, incorporeal undead, swarms of flesh-eating worms, etc.”
“ When you sleep, your soul briefly returns to the place where it was created/goes to when it dies, and seeks nourishment. Everybody's soul is created with a little link (or you could say a greater entity calls it back) to that place so that it can return easily, but upon death, the soul returns via that and annihilates the link as if returns.
Also, as an added thingy, you could say the entity supplying the link, or residue of the links themselves, (whichever) is the source of all arcane power.”