WHM in its current state really only has Fluid Aura to work with in terms of opening its DPS options, short of adding new or discontinued abilities to it. The rest of the toolkit is fairly straight forward so it would be hard to try and add additional effects to them.

Personally, I'd like if Fluid Aura was changed into a frontal cone AoE with a slow effect on a 60s CD so that SCH could get back Shadow Flare but barring that, I can't really see much leeway in its current toolkit for making DPSing as a WHM more engaging. I could think of other things for WHM, like adding charges to DB, reducing the CD on PoM down to 120 or having PI mitigate damage while up, but that's about it really.