A couple of those items date to D&D 3.5 which had no skill ranks given for enhancement bonuses to Int; skill ranks are assumed in PF as per zza ni's first link. By being the first such item written up in PF the headband is the default.
A couple of those items date to D&D 3.5 which had no skill ranks given for enhancement bonuses to Int; skill ranks are assumed in PF as per zza ni's first link. By being the first such item written up in PF the headband is the default.