A nickname for medieval names such as Richenza and Rikissa, which were derived from the Germanic name Richiza. RIxa could easily be adapted for modern use, particularly if you're looking to honor a Richard.

The ancient mother name from which Richeza, Richenza, Rikissa, and Rixa were spawned. Richiza was derived from the Germanic root ric, meaning "mighty" or "wealthy." The classic masculine name Richard comes from the same origins.