So, this is something I came up with, while hiding on the Paladin boards at work (it's easier to post there on a phone than it is to mod here. )
Shadow Orbs are "great, wonderful, bland" in that they focus on two and only two spells. So much for a "secondary resource".
Now. Here's my idea to give something else for Shadow to play with.
Dark Embrace
Requires Vampiric Embrace
2 Minute Cooldown
Consume your Shadow Orbs. Your friendly target is infused with dark invigoration, gaining health from X% (per shadow orb) of your damage for 8 seconds.
Baseline it could be 6/13/20%, increased with mastery. Toss in a Major Glyph that sets the cooldown to one minute when not used on yourself, and what do you think?