Yea at the time this was one of my better bugs. Had an extremely large array of uses and led to countless other bugs that I found including deleting opponents stake items.
Basically what happens is your character cannot have his weapon unequipped by the game or by even trying to change weapons. The only way to remove it is by manually unequipping it. Unfortunately it only works with Darklight, but still has many uses.
This is the only picture I have since I deleted most of my folders. It shows my character in Gnomeball with his weapon equipped.
This is another old bug so no guarentees it still works.
1. First you need to have completed Demon Slayer and obtained Silverlight.
2. Then you need to get to the part in the Shadow of Storm quest where you defeat the beast.
3. An interface should pop up saying your sword has been infused with the blood of something. Do not click continue through the interface, just click off the screen somewhere to cancel out of it.
4. Whenever you have Darklight equipped it will become a Sticky Weapon and whenever you try to switch a weapon or the game tries to remove it the interface will pop up and block it.