"The guards aided us."
Am I right in guessing that 'av is the verb for "guard" since Suv is "fight" and SuvwI' is "fighter?"
Yes, that is correct. Be careful about overgeneralizing though. A DeghwI' is a "helmsman", but we know of no related verb meaning "to steer" (though there is a word considered to be slang and non-standard, Degh which means something like "lack a plan, but take action anyway").