[Facts] Re: Argantael and the Old Breton “hael”
Older Indo European languages have nouns and adjectives with many cases ending in -s. So words beginning with s were prone to rebracketing. -s sagilos becomes -s agilos and the h is added to restore an initial consonant. More recently rebracketing results in a nadder and a napron becoming an adder and an apron, and an eft becoming a newt.