Flamberge is unsheathable, i.e. if you attempt to draw another weapon the flamberge will be dropped. This is a realistic feature because the flamberge (actually a zweihänder flamberge (flameblades can be in many shapes and sizes) and ought to just be called "Zweihänder" because of its size) and other zweihänders never had a sheath. They were too long for that, and were just carried over the shoulder like a pike or other polearm.
( Actually the Zweihänder swords pretty much were polearms, but with a very long blade, and the general fighting style with them was more like using spears and bills than using a longsword. )