Here's what I've got for period Russian knightly titles:
I'll be grateful for any additional documentation, because the other options I've found just aren't used enough in the period
sources for me to be sure they're appropriate and, perhaps more importantly, will be registerable.
>------- Original Message -------
>I would very much second the idea of "Vityaz" as a likely appropriate term
>"Latnik" (ÌÁÔÎÉË) is a somewhat archaic word that might work, as well
(especially with its use of "laty" or armor as the root).