Basically, I found this as 8-slot a few days ago, put an absolute butt load of time and resources (borrowed some from a friend on a promise to pay them back and then some once sold >.>) into augmenting this, only for it to suddenly become bound to me out of nowhere. 13*s are not supposed to bind to your account unless you buy them off the market. I never equipped this weapon either.
Fairly certain this is a bug. Other people can enhance, augment and sell 13* weapons they've found, as shown by the hundreds of +35 clearly augmented weapons with "Noble xxxx" on them. So why is this weapon I'm not going to use suddenly bound to me?
If this is a bug, I'd like it to be rectified as soon as possible please. The only possible explanation I can think of for this having happened is that I used an account-bound gix weapon purchased off the market to get the "sentence casting" augment factor onto it. I don't think that's supposed to matter though.