One thing you missed out about nicknames, Don (or got wrong if your "From the Latin Nicuel…" is intended to give the origin of the word). Originally they were eke-names, eke in the sense of something extra. There is a phenomenon in languages known as provection, which is the technical term in linguistics for the transferral of the final consonant from one word to the start of the next. Newt & nickname are two good examples. Originally, it was an ewt and an eke-name.

Although it's not technically provection, the opposite transferral also occurs. A napron & a nuncle, became an apron & an uncle. And such transferrals aren't unique to English. We got orange as orange from French / Italian, but originally it was norange!