Q

A 14th Century use of a word is pretty old. However the word is undoubtedly much older than that.

Geoffrey of Monmouth, in Historia Regum Britanniae 1136-1138 gives an ealier authority (Walter Calenius) as saying that the daughter of Hengist used the term.

.. this lady [Rowena], the daughter of Hengist, knelt down on the approach of the King [Vortigern] and, presenting him with a cup of wine, exclaimed, "Lord King waes heil", that is, literally, "health be to you".

Even if Hengist's daughter didn't actually say that, Geoffrey reported it before the middle of the 12th Century and, what's more, he appears to have used the Old English version of the word. I think that suggests the word was used quite widely by the Anglo Saxons (I haven't found a direct OE quote, but Monks didn't use words like that much ... neither did they use words about sex. "Fuck" doesn't appear in print until the 15th Century).

Geoffrey's quote would support the view that the story was in oral currency before his time, anyway.

Please be aware that quoting an earliest reference just means that something is earlier than the reference not the other way round.

:-)
Ian