Ringblade

Weapon (shortsword), very rare (requires attunement)

This ornate +2 shortsword has a cleaving edge and deals slashing damage rather than piercing damage.

Its trailing edge is unsharpened and engraved with mystic runes. When attuning the ringblade, you can also attune a magic ring, embedding it into the circular gap within the ringblade’s hilt. You gain all the benefits of wearing the ring, but the ring and sword together count as only a single attuned item. You can instead embed a ring of adamantine or silver into the ringblade’s open ring. This allows the ringblade to be treated as a weapon of that material for the purpose of overcoming resistance to damage.

Epic Attunement. You can attune two magical rings into the ringblade, which still counts as only a single attuned item.