I'm of the opinion that any Smn that's beaten the Odin trial should have the use of Zantetsuken as a LB3. Though the chance of Odin appearing should be kept random, just like the Final Fantasy games of old. So insert the new 3.O - LB3 and add a 0.1% chance of Odin appearing and doing a Zantetsuken.
As for the new Smn spell that was showcased in the benchmark video, it looks like its a upgraded tri-disaster spell (which in its current form is useless ).