Doublade (5e Creature)
From D&D Wiki
Small undead, any alignment
Saving Throws Dex +4
False Appearance. While the doublade remains motionless, it is indistinguishable from two normal swords.
No Guard. At the start of its turn, the doublade can gain advantage on all melee weapon attack rolls it makes during that turn, but attack rolls against it have advantage until the start of its next turn.
Multiattack. The doublade makes two greatsword attacks.
Greatsword. Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit: 9 (2d6 + 2) slashing damage.
The doublade, a product of the union of two honedge, acts as one creature, with both blades slashing at whatever unfortunate creatures has incurred its wrath. Even so, the doublade is typically unhappy with its arrangement as a pair of swords, and soon reshapes itself into a mightier aegislash.