Enevhar Aldarion
Hero
I don't know, IMO a +1 weapon is always ordinary, always generic, always tossable, never special and never worth questing for. It doesn't matter how many special features you add to it, it will never really amaze me. If anything it becomes ten times better the moment you drop the +1. 5% extra chance to hit is something only a powergamer would salivate over. To me, it is underwhelming, dull, and a waste of time.
The +1 was important up until 5E because it signified that the weapon could injure creatures only hurt by magic weapons. But 5E changed that so that any magic weapon, whether it had any pluses or not, would hurt creatures resistant or immune to normal damage. So that opens up the creation of all sorts of wacky and different magic weapons that are still functional in battle.
As for the OP, while I tired of 3.X, Pathfinder, and Pathfinder Society play a long time ago, one thing that stuck with me is how you can upgrade magic weapons and armor in Society play. Once you have a magic weapon or armor, you could pay to have the magic in the item upgraded to a higher plus or to have the properties of other already existing magic items added to it. So a player could take his character's +1 sword and upgrade it to +2, add qualities to it like flaming or frost or keen, etc for the cost of gold. Of course, with the standard restrictions in 5E rules for buying magic items, this could be handled in other ways, such as questing for the mage/smith who will be upgrading your weapon or armor.