Hi, a friend of mine has a model 1811 Blucher with an F.W. mark on it, and I believe there is a crown over it.
We assumed that the sword was from WWI and that the F.W. meant Frederich Willhelm, but we're not sure.

I don't have pictures of the sword, but it looks exactly like an 1811 blucher with the protruding scabbard drag.

Any ideas?