A blood red hand is the scarlet hand insignia that Sabrina and Daphne on there parents car dash bored in book 1

The Scarlet Hand is a band of rebelling everafters. They want to close down the barrier surrounding Ferryport Landing and rule over the humans. Some quit like little Red Riding Hood , Prince Charming, Pinoccio and Mr Canis ( big bad wolf but later ). The master of the scarlet hand is none other than Mirror, the Grimm's 'closest' (ha!) friend.