Unless I'm missing something, (Atma of the) Smiting Blow is an atma. People use elemental skills for brewing because of the way damage is calculated. MNK's best brewing skill is Cataclysm, which is awful for Rani (and Shinryu) because it's dark based. The next best thing I can think of would be Flash Nova. People use Atma of the Smiting Blow (as well as Ultimate and Beyond, I think) when brewing with Cataclysm because it gives a 100% TP bonus.

I assume the weapon skill you're actually talking about is Victory Smite. I guess that works if you haven't skilled up Club or Staff, but an elemental weaponskill will always do more damage. I've only done Rani once since coming back so I'm not sure how the healing mechanic works, but I assume you only heal it with a skillchain if you do it while it's casting a spell.