I mean, say what you like about their damage ourputs, but I would place the Demon's Spear as one of the top weapons in PVP just because its insane reach and the fact that it is still mildly decent with little to no stat investment (and you kind of do invest some stats to it in builds). The DSS requires some investment, but its damage is noticeable and can make quick work of you. If for some reason, you actually force them to switch from 2H to spear&shield, they have the option to turtle you and even poke you for good damage with the Leo Ring (and that nerf rarely means anything because they'll just do it more slowly; you can't chase them forever).
How do you kill something you can't hit? Most spear users CAN chip damage you with lightning and even magic if it's the Butterfly Spear.