Referring to a knight.

[caiusbeerquitius]

But the English word is not derived from or even connected to the German one.

So what now?

As far as I can see we talk about dialects of the same language, but any linguist hearing this would climb up the wall probably...
At least this information is enough for me, anything that goes more into depth about exactly when which dialect derived from which other dialect is IMHO "for linguists only".

I just looked it up in my "Althochdeutsch" Lexikon.
Uwe is right. What you are referring to with "cniht" is simply a different form of writing, not of pronunciation. The words have the same old-high-German root.

See this statement in the context of what I just wrote above. You are right about my mistaking of the word 'root' here. Anyway, at the time they had pretty much the same meaning.

Yes, connected, yes, similar meaning. Finish.

As far as I can remember from university the oldest form of german known to us through texts is gothic. Then next there are several texts in old high german. My prof always stated repeatedly, that the forms of reconstructed early dialects (by re-doing the Lautverschiebung etc.) are artificial languages, as we do not REALLY know, whether the reconstructed form is right in every case. So we move in a sea of speculations here, I would assume.