What does this strange symbol that appeared during weapon improvement mean?

I went to improve some weapons, and I was sorting through my list when I noticed a symbol next to a weapon's name. It was green and it looked like an arrow with some sort of vines or swirls around it. What does this mean?

Oh, not sure if this matters or not, but it was the Axe of Whiterun.

It means the item has had poison applied. So the next time you use the weapon the poison will be used and the symbol will disappear.

You're talking about the symbol in the upper left, correct? It means your weapon was either cursed or poisoned. It will eventually go away on its own. When you have it Equipped, look at your stats - magicka, health, strength - one of them should be in the Red. It takes a long time to go away, but I also went to a shrine of Talos to be sure. A shrine of Talos removes all curses and ill effects, but this may not apply to equipment. All I know is this just happened to me and it took a few hours of real playing time for it to go away.

It would be helpful if you posted a screen shot but i would say that the weapon is poisoned. if this isn't the case please post a screenshot it would make it a lot easier.

It means you have poisoned your weapon or used a poison on it.