I imagine this question must have come up before over the years, and likely even has an official answer. Still, Google turned up nothing for me:

What do you call the unit of weight used in Tamriel/The Elder Scrolls games? In my mind, I say "pounds" because I'm American, "feathers" because of the icon (at least in Oblivion), or "stones" because it sounds old-timey British ("kilograms" sounds new and modern, so that's out). And every time I do, I doubt myself. Inquiring mes want to know.

Some thing was mentioned in the book about Orcs, called, The Pig Children

Angaids seems to be weight, and pertans in height. ALthough I have no idea what these translate too.

That's certainly closer to an answer than I could come up with, though it seems doubtful that the body weight of even an orc is 93 *times* greater than a full set of Daedric armor.

Hmmm.... True. I don't know if there is any dialogue in game that hints at what it is. It may just remain a mystery.

I'm not sure if this counts as canon, but in Arena and Daggerfall, kilograms were the system of weight, in the character creation I noticed it said: "Carry Weight: ___ Kilos."