When you get to Bishop Ladja at Talon Tower, makes sure you're at least around level 34. Keep your son at the back of your party so he doesn't receive damage often. Have Saber at "Show No Mercy" and use Oomph on him when he increases his attack power. be sure to use Kazing to revive your party if they die. Keep attacking Ladja while healing and reviving, as well as using Oomph on Saber when he increases his attack power, to defeat Ladja. Note: If you're at level 37, you can also try setting your party (Saber, your son, and your daughter) to "Show No Mercy".