As far as the naming 'issue' with the various force weapons, it makes sense from a rules perspective. Nemesis Force weapons already have several special rules attached to them, thus it's easier on the player and his opponent (who may not have the codex or be familiar with it) to have all weapons that do the same thing share a similar label. It avoids any confusion on what uses the Grey Knight nemesis rules, and what's just a 'normal' force weapon.
Much like how plasma, shuriken, las, splinter, blaster, and melta weapons tend to share the same labels while having varied sizes but a similar ability,