Middle English shethe, “close-fitting case or covering for a blade,” from Old English sceaþ, scæþ, from Proto-Germanic *skaith- (source also of Old Saxon scethia, Old Norse skeiðir (plural), Old Frisian skethe, Middle Dutch schede, Dutch schede, Old High German skaida, German scheide “a sheath, scabbard”), perhaps from an extended form of PIE root *skei- “to cut, split,” on the notion of a split stick with the sword blade inserted.
Fun fact, the German word for scabbard is “Scheide” which also means vagina.
That is a fun fact! Looks like sheath in English is a cognate with the same etymology
and vagina is just the Latin word for sheath
something about men and their swords, I guess
https://www.etymonline.com/word/sheath
And the word “vagina” is Latin for scabbard