One of the Super Abilities used by Kirby in Kirby's Return to Dream Land and its remake.
It also appears in the Super Smash Bros. series as a Final Smash.
It allows Kirby to use a large sword in the form of the titular ultra sword, or a similar object to defeat enemies and destroy certain parts of the terrain.
Multiple variations can appear:
This tag implicates sword_kirby (learn more).