|Martin Weil Venture-Agent aka kinevon|
The point you are missing is trying to define just what a named magic item is. Traditionally speaking in the context of gaming, a named item is simply something like "Muser's Rapier". It may or may not have any exceptional magical abilities, (being just a +1 Rapier that the folkhero Muser used 362 years ago when he fended off a Goblin horde until he fell to their overwhelming numbers). Its still just a +1 Rapier, but with a name and back story.
And at least one of your examples is something that is explicitly not magic, so it doesn't fall into the named MAGIC item rules.
And, to be honest, "Muser's Rapier" cannot be upgraded, at least, not if you want it to remain "Muser's Rapier". Once it changes from matching Muser's Rapier, in any fashion, it is no longer Muser's Rapier.
And, another thing to remember, is that the no upgrading named items rule is to, yet again, avoid table variation.
For Celestial Armor, as an example, there are several ways to break out the cost, which wind up with different costs for upgrading it from +3 to +4.
So, instead of adding a novel to cover all the possible named magical items, and the costs to upgrade each one in PFS, they just said, "No.".