It seems like the visible pieces for a set and the non-visible pieces for a set are basically different sets - the non-visible even have a different name ("soft" bazu, "worn" magnetic). They are of different calibers of gear, and have different classes who can wear (chain vs hybrid, plate vs pure melee). Within a subset (magnetic visible, bazu non-visible, etc) they seem to be relatively consistant, though some pieces are better than others (naturally) and there are some exceptions (i.e. magnetic bracer).
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