Ignoring the Soulbind, I actually assumed that an obvious thing to help balance out the Convenant abilities via conduits.
Divine Toll kind of does this, adding a chance of single target burst into a stereotypical aoe ability.
Add some give and take to the editing of the ability
Vampire Demon hunter sinful brand, add a conduit that allows it to hit 2 other targets for a % of damage, but lower the duration. Not saying it is a great example, just points the direction I thought they were gonna go.