I just posted some valuable infos about Fast Blade II for WHM SCH GEO and RDM in the "Onion Sword III for dd WHM" post, also tbh MNK could also be an amazing fast blade ii user apart from DNC.
Throughout this week i'll record footage of in game proper shenanigans with this weapon and then i'll publish the showcases with also the pics n description of the simulations, the builds, the various tiers of buffs you can do depending on the job and how much atk/accuracy you need to reach (mostly to figure out if one can squeeze in etudes + geo DEX etc)
In general Fast Blade II can be terrible if used poorly single wielding with bad gearsets for it, or insanely good if used properly dual wielding with tons of MA to get those juicy TA/QA procs for 99k bursts on virtually any job.