The power with this lies in modelling and narrative - if I want my legion command squad all to have swords and shields for example, because it looks cool and they're imperial fists, I'm not necessarily punished for taking the less good power weapon option. It's why we saw so many special character conversions in 3rd, it didn't matter whether the guy had a sword, axe, mace or power-chainsaw, they were all functionally the same.