Yep, I postponed the attack until I had some more heavy cavalry. I took some archers but not all, enough to kill his spearmen without losing too many of them against so much swordmen. Same with the spearmen, enough to bother his cavalry but not too many to reduce loses against the swordmen. I went with cavalry and swordmen in full.
He got the nasty surprise of another 1,5k heavy spearmen which hurt my cavalry bad, but at the same time were a boost to my swordmen efficiency in battle.
I actually love the combat system of this game, it looks very realistic. Too many people at low levels always go with their army in full, while you face them selecting your troops based on their army composition. And then they get annoyed due to the difference in losses, they seem not to understand how important morale is in a battle (in history many large armies have been defeated by smaller forces just because they were getting slaughtered, so the rest flew).
Gratz to the developers, good job. Too bad now I would like many more type of units to mix around