New Characters
Caezar: His stats aren’t great. I don’t recommend him.
Raddy: He comes at level 1 but has great stat growths. Use him if you haven’t trained Oguma or Navarre.
Strategy
Move one of your high movement units to the armory and shop to buy all you may need, have Sheeda attack the axe fighter. Don’t worry about her being damaged, she won’t be attacked during the enemy’s turn. The axe fighter will drop a silver axe that you can sell for a good price or give it to one of your axe fighters.
Two of your units with high defense should move to the spaces marked in the image below, one of them should have the Knight Killer. This is one of the few occasions in which Banetou is useful. Move Sheeda to the north.
Have Sheeda stand near one of the archers, but make sure she can’t be hit. This will help you to slow down some units so your main group won’t have to face too many units at once.
Keep luring with Sheeda and take care of all the enemies as fast as possible.
Once all the enemies are gone, advance to the castle; reinforcements will be coming from the forts, so have some characters stand in the spaces shown in the picture below, while Marth and someone with the Armour Killer or Maric kill the boss.