He got 6 units on you with his offensive, and all were more expensive than yours. So far it's nearly cost-even, so if you think you can get a few units up on him with an offensive, I'd go ahead. This is probably his full force since he would have attacked harder if he had the manpower - it was down to 1 defence units at the end.
I have several knights and Acav's that could make the trip in a few clicks. More where they came from, too. Hang tight and keep a cover of at least his amount of (remaining, assuming a bad roll of rng luck) offensive units. If you can't get that cover, don't attack. He's got 2 elite promotions though, so I'd hope for the best there and cross my fingers you can take that knight out.