An ability, that my own sword's design has as well. Catching incoming spells is an effective way to do battle with spell casters. However, the number of spell storing should be limited, to make the game fair for all.

Since the gem stores the spell, I assume it releases it as well, back to the target of the sword user. Or maybe it just sends it back into the Weave and during dismantling of the magic, it keeps the sword in top form.

My own sword design allows it to store 3 spells, which is instantly known and usable, and must be released back at any valid target, since if a fourth one is coming, it will force out one of the previous one, but with a random target save the wielder. So it is designed to be a spell swallowing defense and quick reflect shield and be used as a sword secondary. Not easy to master and build your fighting style around it, but when you do, casters are practically denied a direct attack. Still can cast magic to summon beasts or target the ceiling to make it fall on the sword wielder tho', that is why it protects only at direct effects and damaging spells.

It's truly a beautiful sword and a magnificent art piece <3

thank you!