sheathing a wet or bloody sword

It probably did happen, though I'm guessing most people would have preferred to clean it off first.

This is just my opinion, and I can't stress that enough, but I think it could be that the blood would stain, perhaps leading to rust; however, I think it has more to do with the fact that a stain is essentially added material to an object. You add material to the edge of a sword and it dulls pretty quickly. Without proper solvents, it's difficult to get stains out of something, particularly if it's something as delicate as an edge, where you could easily slice off your fingers just by cleaning it. In most cases, if you didn't have time to properly clean the blade (though I can't imagine why you wouldn't, since the only time you'd sheath your blade is once all your enemies are dead, in which case you could easily give it a proper wipe down in place of a proper cleaning, since you wouldn't take those into combat with you), then you'd just flick the majority of the blood from the blade and sheath it until you could clean it. In addition, since only the exterior of a wood scabbard would likely be treated against the elements, shoving a bloody sword into it could cause it to swell and crack, so, on the whole, not sensible at all.

But again, this is purely conjecture, so take it as you will.

Did it happen? Probably. Often? We don't know, but all signs point to "probably not so much". Why not? Back when swords were a practical weapon, most people had a general idea of how to take care of edged weapons-- keep them oiled, keep them clean, don't let the scabbard get wet, etc. For an example, in one of... Ed Fowler's, I think, knife books, he comments on how his grandmother had this old kitchen knife, carbon steel, that she'd had forever. Never washed it beyond rinsing it off and then a little fat on the blade; he still had the knife, I think. That's the kind of thing people would know how to do because they didn't have the money to afford buying new blades like we do now.

That's something that a lot of people, I think, don't really get-- just how rare it was back in the day to buy replacements. They'd use a kitchen knife until it was worn down to a sliver... and then use that sliver to peel potatoes or something after they got a new knife. Doesn't go just for weapons-- could go for, well, pretty much anything made by a craftsman as opposed to something that a person could knock out at home. This held true pretty much throughout history up until very recently with the Industrial Revolution, when mass production became a reality and different materials became widely available (stainless, for example). Taking care of their goods was far more of a priority than it is today. Kind of a shame it isn't still that way...

That said, I do agree that oftentimes there was probably not much time for more than a cursory wipe-down of the blade before sliding it into the scabbard. Just depended on the circumstances. A baron after a formal duel might have handed his sword to one of his retainers, who would've cleaned it up properly-- but the same baron, in the middle of, say, Crecy or Agincourt, probably would've kept his sword out and ready to use. In some circumstances you just don't put your sword away until the noise stops... and when the noise stops, either you don't need your sword anymore (dead/incapacitated/prisoner) or you've got all the time in the world to take proper care of the blade. Or to hunt up a living footman to take care of it for you, of course...

My copliments Elheru for the excellent post. You captured my thoughts...

LOL

Excellent point....though sometimes when I stick my sword in clean and it comes out bloody, I just stick it back in again.....I can't afford a new one and it really only happens about once a month.