...Yup, jumped into the bandwagon too, i present you: Jarosite and Hornblende.

Jarosite and Hornblende were earth-made gems that were categorized as faulty and were in queue for the forced-fusion program. While Jarosite escaped unharmed, Hornblende was badly damaged and her gem almost shattered. In order to help her colleague, Hornblende willingly trapped herself into a hilt, giving her the form of a sword with a shape-shifting blade. Now both roam the earth, incognito, but willing to help anyone in danger. Both share a deep hatred for the homeworld and fusions, for they think that they can only make monsters.

Jarosite's Gem Weapon is actually no weapon, but rather a suit of armor that expands or retracts depending on the mood, going from a simple chestplate that covers her gem when relaxed, to a full-set when in angry.

Hornblende might not serve much as an individual, but she can choose wether she forms a blade or not, so she can't be used against Jaro.

"They got what they wanted, two gems thinking as one. Now we'll get what we want."

Their theme would be something akin to: https://www.youtube.com/watch?v=6vW1Za9LHUU