Just posted in another thread regarding glitches, but I totally forgot about my disappearing sword!
I was exploiting the sneak to 100 'glitch' with the Greybeards last night, when by mistake, I hit one and he attacked. He disarmed me, and knocked my sword out of my hand, I ran to avoid death, to the next room. He calmed down eventually and I went to get my sword of the floor. Gone. I searched the room, the next room, the next room, the roof, pots, walls - THE LOT. I can only imagine his frosty powers made is disintegrate or its stuck under a texture in the floor. NOt the best sword, just my fave and best I had.