Was shown in a treasure pool from Walk of Echoes Conflux #5 (Wyverns + Hydra Boss) on Titan server.
Seems the lower tier Confluxes have to be defeated enough times to open up the higher tier ones. Whether this has to happen within a conquest week, or just once overall is currently unknown.
great for damaging quick draws and leaden salute. also not bad for qd acc with the 4agi, so all around this is great for cor. best back ive seen. wonder how you get it.