She tries out the first function. Carefully, on a small pebble. One does not recklessly play with novel spells that can fling hundred-kilograms paving stones around.
...even with a small mass, it's restricted to a very slow speed and a short range. More safeties; if you want to replace an actual cannon (railgun?) you need use the third variant. (Tanya approves! More spell designers should think about including safeties, especially in mass-market items people might use without rigorous training! This ring could be used by civilians!)
The really unfamiliar part is how it, once again, implants knowledge in her mind. She knows they have spells to do that and she still can't grasp the full implications.
"Very interesting," she says, returning the ring to Iomedae. "I could control the spell while it was ongoing just as if I had cast it, without feeding it mana. Hooking it up to my mind must be the actually complicated part of this particular spell; applying force to an object is simple and the amount of force is hardcoded, keyed to the object's inertia." She can see why the the local 'wizards' would need to do that complex work up front, to make spells available later and usable at a moment's notice. The ring must be performing any required calculations, although this particular spell wouldn't need much of that anyway; she's still not clear on how wizards do that part. Or - if they can bind magic to tangible forms, perhaps can they perform computations using the magic itself, and the magical structure that does it is what takes so long to set up? In that case, they actually have a very elegant solution that doesn't rely on external computation devices at all!