Medieval depictions of cherubim and seraphim are often conflated. Since
it appears in association with Ezechiel, this should really be a cherub,
since that is the class of angels described several times in his visions.
However, this creature clearly has six wings, not the four described by
Ezechiel. Seraphim are only mentioned in the OT by Isaiah (6:2-3), where
he describes them having six wings, two covering their feet, two covering
their faces and two for flying with. Clearly the figure in this window
is an amalgamation of the two descriptions.