Through the ages civilizations have risen swiftly only to fall, leaving the ruined bones of their once great halls as proof of their former glory. However, some few relics were too powerful to fade away with their makers and can now be used by anyone strong enough to tame their power. No one knows where they came from or who may have crafted them, but they stand as the sole, potent symbols of long forgotten cultures. Some say they will still remain long after the stones of this era's greatest monuments have diminished to nothing but dust and ash.
Good on characters who can last a while. Juju, Higashi, and Onimaru can last, while Andromeda, Tafari, and Amaya can 'range dance' to maximize its use. The Salve can also help a lot in some mirror matchups, such as Cornelius vs. Cornelius.
Good on - or against - any single-range character, such as Onimaru, Helene, or Ashi. It's also good against characters with powerful moves that cost 50 energy such as Cornelius. It has good synergy with Ubuntu and Andromeda - those with energy-gaining advantages.
Girdle of Iron Will
Used best on characters with a slow, powerful move that they don't want interrupted. Cornelius and Juju are good examples, as are Onimaru and Andromeda. It's also good against stun or intercept-heavy opponents, such as Rumiko, Yoshiro, or Higashi.
The insignia needs to go on a character who relies on single-hit attacks, such as Yoshiro, Higashi, or Anex. It has particular synergy with Marquis LeMorte because his life draining moves benefit doubly from it.
Yellow Rock of Cowards
Works well with Rumiko (because of her safer switching ability) and Marquis LeMorte (he likes switching out anyway). Also good on anyone if you want to get the take off the last few hit points from an enemy without having to guess much.
Good on any character, if you have the mindreading powers to back it up. It's especially good on characters that can force a deadly 50/50 guessing game with it, such as Onimaru, Ashi, Cornelius, Juju, or Ubuntu. Just don't equip it on Tafari.