Walkthrough

Fencing Lessons Is a Side Quest in Novigrad with suggested level 12. This quest becomes available after "Broken Flowers", if you agree to give Rosa more "lessons".

If you choose AXII on the thugs:

If you choose to fight them and tell them to piss off:

After talking to Rosa, she leads you to the bridge, where she wishes to fight, with real swords.

After fighting her, she says her corset is shifted, and asks Geralt to turn around.

As Geralt turns around, and then back, Rosa has disappeared.

Use witcher senses, to see the path that Rosa took.

You will find two thugs are harassing Rosa. As you talk to them, tell them to go away, you can pay them off or convince them to apologize.

After dealing with the thugs, there will be a super upset Rosa.