I just made a few custom weapons from modified parts.
The "French axe" is a modified version of the halberd (part 3848). I first saw this mod in BrianofBrick06's Classic Castle avatar.
The double-edged dagger is a modified version of the pike/spear (part 4497). I don't think I got this idea from anywhere else, but I'm sure it's probably been done before!
It's fun to see what you can do with toenail clippers and a fingernail file.