Yeah i would say just get a ranged weapon for democan farming / killing. Even if you have good defense it's not worth trying to rush in with a melee weapon.
If you want good healing i highly recommend Natures wrath, sold by rising waters for 10M or from maze.
No even if you're with a friend and you do more damage or take less hits the loot is random.
I wouldn't say sell but it's probably doing low damage because your magic bonus or the fact that democan has 70k+ HP. Also make sure you're not midair while fighting a democan his screeching attack can kill you very fast, also if you're grinding democan at the end of the road there's a spot where you can get him stuck like on a rock before the new road.
It honestly depends on your damage, Salamander is very good depending on which one you have. I would say use Salamander Blade of throne Darktoad Celestial and possibly greater storms because of it's ultimate.
I mean it kinda depends on your magic / melee damage, they're both good for healing i prefer darktoad but that's just me. If you want good healing then you should probably get Natures Wrath spellbook sold for 10M by rising waters or from maze.