A very easy glitch to keep the sword before the game removes it!
Step #1: Reach the dream sequence
This happens right after you get knocked out by Runt.
When you are within the Dream sequence you can progress like normal, but instead of walking up to your parent's body, walk around and head to your home, there will be a container as this map is simply the same 'ruined Skalitz' map but re-shaded differently to look like a new area.
Step #2: Drop the weapon into container
Because the game somehow arms you with the sword, but not as a 'Quest' item anymore, but a regular weapon, you can now transfer this sword to any containers, resulting in you being able to avoid having it removed from the game at all!
Put it into the container!
Step #3: Finish Dream Sequence, and Retrieve sword!
Finish this sequence and wake up in Rattay, then make your way back to Skalitz and pick up your goods in your home's chest!
Congradulations! You have now gotten a weapon that is cool looking but overshadowed and outclassed by other ingame weapons!