Something I did think about though with the Rune Knight, you can only put one rune on a single item. So, your armor gets one rune, your shield gets one rune (or your offhand weapon) and your weapon gets one rune. What do you do with a fourth and eventually fifth rune?
I mean, they specifically use the language "wearing or carrying" an item inscribed with a rune. Does that mean carrying it in my hand, or simply carrying it on my person? If I have 4 runes, - armor, shield, weapon and weapon, do I need to put away one weapon to use the other weapon's rune?
It's not entirely clear. And it could lead to some pretty weird situations at high level where I'm pulling out weapons, invoking the rune, tossing the weapon and pulling out another weapon just to use another rune the next round. Which is going to run into issues when the fighter doesn't want to chuck his flaming longsword to pull out his non-magical axe just to invoke a different rune.