One thing I think that would be interesting and also rewarding is to have the glory sword upgrade-able like the Onyx shield. That way even when people have the stats for Obsidian gear since the sword is so rare and hard to make, you can upgrade it to be better and useful at those levels. Both Onyx and Glory sword should have like 3 or 4 total upgrade levels since they're the farmable unique gear. Glory(IV), Onyx(IV) or however high you'd want to make it. Just an idea.

 Even the idea of regular armor sets having the ability to upgrade to higher tiers would be cool. Like Obsidian Breastplate (II) by investing more money, coal, and obsidian ore/bars into the pieces of armor. It would create a great way to put money back into our progress so it doesn't just stack to the infinites.

Alot like you have the talismans doing now.