Warrior Final Attack after Big Bang

Apparently, after BB, it no longer affects either your mobility or the rate at which you can spam attacks.
So regardless of whether you're running around Slash Blasting mushies, or standing still spamming Intrepid Slash at HT, whatever tiny damage bonus FA gives is welcome.

The question that remains is whether there is a place to put those SP that will be more beneficial.

There isn't a place to put them otherwise. I'm not telling people to put them somewhere otherwise. I'm saying that Final Attack does not give a significant bonus damage to training. It's not pineappleing hard to understand. It just simply doesn't.

And no, Pre-Big Bang experience is not the same as Post-Big Bang experience so shut the pineapple up about that.