I'm not seeing a great way to track this new change to Molten Whip. Once you use the empowered whip the Seething Fury buff goes away in the UI. You still have the weapon/spell damage buff though for 15s. I can't find anything to track that to make sure it stays up.
I could try to track my weapon and spell damage but that can be all over the place with raid buffs going in and out.