Would sheathed sword be considered an improvised weapon?

@JeremyECrawford Would fighting with your sword sheathed be considered an improvised weapon, thus done with Disadvantage? #randomthoughts

— The Dragon Fisters (@DragonFisters) September 25, 2015

DM's call. To me, a weapon is improvised if used counter to its design (e.g., a slashing weapon not slashing). #DnD https://t.co/Y8pwT7QvMw

— Jeremy Crawford (@JeremyECrawford) October 9, 2015