So the enchantress follower Eirena can equip a number of melee weapons, but she is magical range. Does she benefit from the damage of her melee weapons? Do they cause her magic bolts to do more damage? Or can she melee with them if a enemy gets close? If not the other melee weapons, do staves/wands at least boost her magical attack?
Something I read said she especially benefits from arcane boosting, why?
Followers get the benefit of any weapon they equip, I'm not sure about how you say she gets additional boosts from arcane though.
Same as say, a Wizard, casting spells with a sword or axe equipped, it doesn't matter what type of weapon you give to your Sorceress.
The damage of any of your followers will benefit from the weapon damage (the big digits on the weapon specs) of their equip weapon regardless of its type ( as long as they can equip it), plus any bonus stat attributes on the weapon (str for kormac, dex for lindow, int for eirena) will be doubled and thus directly adding to the damage output of your follower.
I'm not sure about what you mean with arcane damage though
In Diablo III, the only class that is dependent on a certain type of weapon is the Demon Hunter. With the DH, casting certain spells requires that a bow, crossbow, or hand crossbow be equipped. For all other classes, including followers, the weapon type does not influence the types of spells that can be cast, and any weapon influences the damage of all spells, abilities, or attacks equally.
So a wizard can use a wand, axe, sword, or any other weapon and cast both melee and ranged abilities, with the damage increasing for all of them. The same is true for the witch doctor. One currently popular build for the witch doctor relies on the ceremonial knife Starmetal Kukri, but involves casting poison darts, a ranged ability. The damage of the poison darts is directly related to the damage on the weapon.
