Do those references refer only to the modern use? The modern word is certainly (re-)borrowed from the Old Norse, which I state. The question is where did the Norse word come from and how does it relate to the Old English wicing?
In this case, the dating is pretty clear. The Norse word doesn’t appear until much later than the Old English, and the semantic development of the Old English word is clear—it did not originally mean a Norse raider (not to mention the early uses pre-date the Viking era). It’s certainly possible that the Old Norse word developed independently from a cognate root, but as I say I think it “likely” that the Norse word comes from the Old English.
The Fell article is the most complete discussion I’ve found on the topic, although it doesn’t address the development of the Norse word.
Is there any reason why the old English word wicing couldn’t, or shouldn’t, have been used, in those early glossaries you mention, in reference to people such as the Germanic invaders (Hengist, Horsa) who arrived in England in ships, centuries before the Norsemen, and set up their encampments in Kent and thereabouts?
It’s not used in that context in any of the extant manuscripts. Wicing has a negative connotation, and it is unlikely the Anglo-Saxons would have applied it to their forebears, whom they tended to valorize.