I've just read today that the matter manipulator is going to have upgrades.So I think it could be fun to put a whip-like upgrade for it, for example you'll be able to grab a foe and throw it away, something like that.
I would like to see how it could be used as a weapon... Hmhmm.. Oh, ho! I thought of something... But let me just have some fun with this. Manipulator, Separator, and (That ranged one) Manipulator (magic-like): slowly deconstructs your enemies into their basic molecules. Separator (Melee): Melee weapons made out of dirt, cobblestone, steel blocks, slime, direstone, etc... (That Ranged Class) Allows you to fire off blocks as projectiles. From one block rapid fire, To charging up a huge cannon ball of dirt, cobblestone, etc...
While it would be entertaining to be able to use the matter manipulator as an offensive weapon (as I already stated in the "It should start and end with the matter manipulator" thread), I think it is very important to keep any offensive capabilities of the MM at an underpowered level. If it became too powerful you'd have no reason to carry anything other than the matter manipulator ever, making just about every equipment in the game redundant and resulting in a rather bland game, it could however be entertaining as a weapon, slowly deconstructing enemies into base components, not fast or efficient but just because they are made from matter too so why the hell not.