Is it possible? Yes
Is it easy? No
Doing it would require tons of work and making the specials and animations compatible between all the types. Each weapon type would require the creation of the animation/config details for each special attack.
It might come but only after getting the mod in a near perfect state.
Just adding support for specials of the same type for all weapons takes time/coding/fixing/testing. Now imagine adding support for everything to work on any weapon. Chaos xD

oh ok... thank you for the reply.

can you make a grenade launcher with insane firing speed and low damage?

What about just to bring across the second weapon's element or level but not allow the secondary fire?

Well, Darknekku seems your mod has near the perfect state that you wanted, hardly any game breaking bug reports, maybe we can get one handed melee <---> two handed melee at somepoint in a large update? Perhaps on a important date (New years, or The mods next anniv. maybe)
i think it would be great to have a tiny little dagger and just kill everything xD

It might be interesting then, to only allow limited functionality cross-type fusion: level, quality and elemental type. Would be a big boon with FU, for example, to add elements and level scale some of those crafted weapons without random-generated analogs.

gun plus gun = gun that fires a gun

Originally posted by ♥♥♥♥ Tard:

gun plus gun = gun that fires a gun

oh yeah, like that shotgun that fires shotguns in Enter the Gungeon