Personally I'm not a fan of making something so good it needs to be simutaneously nerfed to balance it. At what price, power?
For crying out loud, he's a bard, not a blood mage making pacts with dark powers. Can't he sing a few happy songs without inviting Odin's wrath, the baleful eye of Hel, or Loki's slimy touch?
It's safer to be a wizard.