This is happend so many times to me!, the odd floating iron mace etc...at first I was like HOLY HAMMER OF THOR A MAGIC MACE!, it was moments later after several more appeared that I realised 'twas a glitch.
I had this happen with a battle axe but it was spinning on its axis, like the blades in the dwemer ruins XD scared the crap out of me. I couldn't pick it up though. so it was forever alone, spinning floating thingy
LOL. I have yet to come across a floating item that I'm not moving in the air on my own. But I have had the soaring mammoth thing happen to me a couple times. And then from the mammoths become the 'soaring Dovahkinn." I love dying by mammoth lunge, you get to see all of Skyrim for one second as you fall back down slowly.