What player1 said is true, although it's a little misleading given the context.
Weapon abilities increase weapon damage. Some skills' damage are based on weapon damage, such as Crippling Blow. Therefore, those skills would get an indirect damage boost from weapon abilities.
Necromancer skills may do physical damage, but none of them are based on weapon damage, so none of them would receive a buff from weapon abilities. player1 didn't actually say that it would, but given the context, someone could misinterpret it that way.