10Dropped by
what a swing puts on the screen
Each swing launches a star that sheds smaller ornaments behind it as it flies. Those ornaments hang in the air briefly and then drop. Neither the star nor the ornaments pass through terrain, which is the detail that decides where this weapon is good. In a tight corridor most of what you throw dies on the nearest wall. In an open arena the ornaments pile up into a slowly falling curtain that enemies have to walk through to reach you, and the sword ends up doing far more work than the swing itself suggests.
getting one
The Everscream carries it, and the chance improves the deeper into the Frost Moon you are. A run that stalls in the early waves is close to a waste of the summon. Build an arena that lets you survive long enough to reach the later waves rather than resetting the event over and over from the start.
where it fits
It arrived weak and has been buffed repeatedly, so older advice about it being a novelty no longer holds. Its projectiles now hit for the same weight as the blade itself, which makes it a genuine option for the events it comes from, especially against the ground waves that funnel toward you.