So. Lets think of some of the categories they might come into:
Crystals. The blood of gods shed in the Gods War. This really is the anchor magic item I think. Who doesn’t have a POW storage crystal or a crystal with a spirit in it. I really need to make way more use of that.
Enchanted items. Weapons with spell matrixes, armor with extra AP, weapons that do extra damage. Some might be the result of spells characters cast or Divine Intervention, some might just be magic rituals or whatnot.
Remnants of the Gods Age, First, Second, and Third Councils, or of the God Learners. One-offs, these can be as mighty as Ironbreaker, or some weird draconic resonance device worn as a third eye, a belt of strength, the Wand of Seven Phases, or most of the items in Plunder. Always need more of these rare items as they provide insight into Glorantha. They don’t need to follow the usual rules and can be whatever is needed.
Things made by the Elder Races. A weird lead mace, a Mostali time piece, elf arrows created to always hit true, there’s plenty of this stuff as well. Like the previous category, they don’t need to follow the usual rules and can be whatever is needed.