How sweet would it be, if you were on a wolver den and you had flamberge + dark briar barrage when you came across some lumbers... and instead of being like "oh no, I have all of these piercing-" you could just charge up your flamberge and light into them, dealing the appropriate damage type?
And then a few seconds later, that smoke animation could go and it would return to dealing piercing damage, just in time to kill more wolvers.
Actually, I kind of agree with you Rare. Making it elemental and piercing would make more sense and it would make the item a lot more interesting.
The reason I didn't just say that up front, is because of how mixed damage types don't work very well in Spiral Knights due to the way in which defense is calculated. Enemies have a much larger amount of the defense they resist, and only a bit less defense in the area they are weak to. In the end, you would end up with a weapon that is resisted by 4/6 monster families, so making the item become pure elemental would almost always benefit it more. If the developers patched the game to allow for mixed weapons to work in a similar way to the current pure weapons, then yeah, making these things would be sweet.
I'm not sure about pure elemental (you are after all still poking it with a pointy thing), but having different damage types on some charge attacks would be an interesting mechanic I could definitely get on board with. Perhaps the Flamberge's charge would deal split Piercing/Elemental, or something like Cutter's mechanics with a Piercing hit and simultaneous 'ghost' Elemental hit.
You could even expand it into some other weapons too:
-On Triglav/Sudaruska's charges the first strike could be pure Normal, but the second light-strike could be mixed Normal/Elemental.
-On Wild Hunting Blade's charge, the ghost Wolver hits could be pure piercing
-Torto shield bashes could deal mixed Normal/Special damage type they defend against (ex Savage Tortoise bash deals Normal/Piercing)