Here the verb keda/zw, a variant of [s]keda/nnumi, is glossed with the late skorpi/zw. Same entry in the Etymologicum Gudianum, the Etymologicum Magnum, and a scholion on Homer, Iliad 15.328 (where the aorist passive participle occurs: web address 1). Eustathius comments on the verb in his Commentary on the Iliad.
The present keda/zw is a grammarians' invention, first appearing in Herodian as a variant of keda/w. It is patterned after the Koine use of [dia-]skeda/zw instead of skeda/nnumi (verb equivalent to keda/nnumi), which in turn generalises a present stem from the aorist e)ske/dasa.