The restrictions on items are only for using them (resolving their abilities). Any hero can have any item in their Hero Area.
As for Durgen, he uses actual number of weapons in Hero Areas, regardless of their holders' ability to use them. Thematically, weapons come to life to deal damage.
Is the rule for weapons in hero areas that are in the same location as Durgen?
As opposed to all hero areas regardless of where the hero is.