That happened to me once, you should leave it as lost and create a new save :(
Damn it getting Broken sword to level 100 in upgrades was a pain in the ass now i have to do it again
Yeesh, I was planning on doing that at some point just to see what the last perk is, never got around to it. You remember what it was?
It was just gain more exp I think and here for me I thought it was going to be like the broke sword in Dark Souls maxing the broken sword then get it that one soul then you get the best weapon in the game