How can I add vanilla enchantments to modded items?

I'm creating a Deltarune-based mod and am trying to implement Noelle's ring as a weapon; when you right click, you cast a spell. The plan is that if the ring has Thorns, you cast Snowgrave; otherwise, you cast IceShock. However, here's where I'm stuck; I want to make the ring enchantable with Thorns without changing it to an armor. How can I do this?