I tried this again in my second game. My sovereign, Relias, had a couple of extra swords and some patchwork armor that he didn't need. I had hired the mercenary Arvix, so I moved him into my army and tried to drag and drop a sword and the armor to him. The sword transferred ok, and I was able to equip him with it, but I could not transfer the patchwork armor. I tried dragging it to him a half a dozen times, and none of them took.
By the way, I got the same graphics problem with the 2 swords. It looks like the two figures are blended together:
There's a saved game here.