Armed Birdie is one of Sabretooth's special attacks, where he summons Birdie to perform a set of three projectiles. It was first introduced in X-Men vs. Street Fighter and would later re-appear in Marvel vs. Capcom 2.
Birdy (misnamed Birdie) is a henchwoman of Sabretooth, appearing to assist him in a few of his moves. Birdy's main motive in assisting Sabertooth was to calm his homicidal urges by telepathic manipulation, which is referred to as glow. She also appears in two of Sabertooth's win poses.