To be able to beat the bandits, the knights who challenge you, as well as the enemies in Kingdom Come Deliverance, you have to be able to reach a certain global level, a certain strength, a certain stage in terms of combat, of aptitude for the sword.
And for that, it’s best to train with Captain Bernard at Talmberg or Captain Robard at Rattay.
Robard will offer you training with a wooden weapon or training with real weapons.
You will then have the choice between the long sword, the short sword, the ax, the spear, the lance, the fight with your bare hands. Then with or without a shield.
This is clearly the fight with bare hands that will boost the statistics of strength and combat as quickly as possible. Then the sword for the sword skill if you prefer this weapon.
Afterwards, you will have to accept the challenges all the time and try to defeat the bandits to keep progressing.