The origin of the -āh extension cannot be established with certainty, but as plausibly argued in Huehnergard 2005 (following Brockelmann 1908:334; cf. Pardee 1999:286, 2000:36), it may represent a back-formation from the plural *ˀil-āh-ūma
PS
*ˀil- - god
(Fronzaroli 1965b:248, 262, 267; Kogan 2015: 179)