Small addon I thought I might as well share that sheaths your weapon. It's a very simple script and likely incompatible with Stay Unsheathed / Sheath. It doesn't have any extra options or customisation, so use one of the others if that's what you want.
Known Issues
Sometimes it goes into a sort of "ending loop" for hunters. idk why.
TBC Classic: Because of how WoW handles sheath in olden times, it'll sheath and bring out your ranged/thrown/wand weapon or whatnot. I have it do a "double check" to try and also sheath that as well.
Maybe future idea:
Add ability for quick slash command that will temporarily stop sheathing function.