Kettlebane

Kettlebane is a Holy Avenger from House Kettlebane only someone of the bloodline and someone who carries the house signet ring can control the sword. The sword can turn into an apparition dressed like a red knight known as the "Red Guardian". This sword takes the form of the owners preference but can only be chosen once. To Benedict Shieldheart in S3E9 - The Guardian he chose unknowing ly a greatsword.