Yes, a positive shard would go into one of those. Since you've already got the imbued shard, you just need to make the best of it. Personally, I'd go for a triple positive blunt weapon. Go Holy/20%Amp/30%Amp, or possibly Good Blast on Tier3 (if you have 30% from PDK or Claw gloves), and make it your undead beater weapon.
A bit of an update, I think I've got a handle on this. If I'm reading the wiki right, a Material/Positive/Opposition gives me 20% Healing Amplification on a Weapon, or Improved Regeneration on an Item.
In either case I'm limited to one of the following Aspects:
Can anyone confirm I'm on the right track, please?