It’s a mandatory item for retal Drain Essence (DE) builds (usually - physical). As such, you want physical/elemental retal mods on it, they make a huge DPS difference. Physical retal DE builds are very tanky and strong ones in endgame, but are very gear-dependant, particulary - on the shield mods.
Build examples for physical retal DE:
https://forums.crateentertainment.com/t/1-1-9-0-the-z-u-c-c-phys-retal-de-oppressor-almost-everything/49993
https://www.grimtools.com/calc/a2dELnLV
Also it’s a nice DE leveling item.
One of the weapon options for physical retal DE builds too, if the rolls are good (casting speed is what you need the most on it).
Do you want to say AAR builds are niche/lackluster? As far as i know, those are top-tier ones. And +3 to disintegration (AAR modifier) is a very sweet thing for those.