I've steered clear of this, because I don't know the answer, but it appears I'm not alone.
I don't believe you can assign an enchantment 'charge' so to speak, to be depleted with use, for anything non-weapon. If you can, I haven't seen or heard of it yet, and I don't recall seeing any other mods with this as an option.
That being said, as a wild guess, you could try enchanting the ring with a staff enchantment as a conjuration weapon (conjure familiar or something) and then add the other effects to the spell box. I have done spells that do conjuration, mage armor, health increases, and magic resistances at once, so I don't know if it will establish a weapon-like charge or not, but it's worth a quick experiment. I'd suggest first trying it in a brand-new plugin. If it works, use it as a guide to reproduce it in your mod. If now, flush it and it's not a mess for you.