I noticed 2H melee weapons and Cannons can hit multiple enemies at once when attacking with them. Are there any other weapon types that can hit multiple enemies with basic attacks? Are there any exceptions to 2H melee weapon types for this matter or do they all hit multiple enemies?
I've tested the following weapons, I believe these are all the weapons you can possibly get. (Mace, Hammer and Polearm don't have corresponding 1h or 2h equivalents like a Sword or an Axe)
I put the 1-handed weapons which are capable of hitting multiple targets in italic (3 in total).
According to one of the load screen hints, Only a few weapons hit multiple targets (aka splash) in a single left click. These are generally shotgonnes, cannons, and several of the 2 handed melee weapons.
I play as an outlander and can attest for the shotgonnes and cannons.