The first part of the word viking, or vik simply means "bay" in nordic languages
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.
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!