https://en.wiktionary.org/wiki/Reconstruction:Proto-Indo-Eur...
Compare Ancient Greek [w]oikos, and all the various ves, vas, wieś, which can be found all over Eastern Europe.
In Icelandic, at least to my knowledge, we have never used Víkingur as an ethnonym (well maybe during a sports game, or among right-wing nationalists). It has always meant raiders. In 2007 there was even a new word dubbed Útrásarvíkingar meaning businessmen who made a bunch of money doing business abroad (buykings would a clever translation of the term).
EDIT: I just remembered that the -ingur suffix can also be used to indicate a temporary state e.g. ruglingur (confusion) and troðningur (trampling [n.]), and was used as such e.g. að fara í víking (to embark to a viking) so víkingur could also mean, a person that embarks to a bay.
In fact I don‘t remember a suffix which attaches to a pronoun. In modern Icelandic at least we like to introduce more pronouns or conjugate them rather then to suffix or prefix them.
If the word was broken as vi-kingur, I think the modern Icelandic would be við-kingur (or við-lingur), which is simply not a word in the language.
A pox o' chads on your house, ya mewlin' landlubber!
https://en.wikipedia.org/wiki/Fossil_word
This can also happen to word roots. Because this is about a historical word, it's interesting to look at the broader Indo-European language tree for clues about the original meaning.