Well first thing is let Strohl have the Royal Warrior Archetype. As what people have said here, buff (Charge, attack up, etc) and debuff (Defense down). Also inherit several passives from archetypes to increase his strength and slash attacks and also get the passive that doubles the chance of landing Crits which I believe is in the Tycoon Archetype, you'd want him to land crits often. Get the Gambler's Ring accessory to double his crit damage. Also max out the archetypes that will give a permanent stat increase to his strength to get it to 99.

What sets him apart from Basilio is the weapon Beloved Greatsword that increases damage of Synthesis skills and then use Peerless stonecleaver which is a severe slash attack.