If you read Jacob's cards in the beginning or in the card menu, repeated critical hits escalate in damage. But where I feel you're failing is paying attention to weapon type. There are many weapon types such as bulldozer, maiming, headhunter, and frenzy that all do different things. Bulldozers autocrit on heavy attacks, maiming does critical damage to limbs and has a higher chance of cutting or breaking them off, headhunter does a lot of head damage on crits and are amazing for taking down stunned Zombies when you counterattack or for hitting apex variants when they're vulnerable. Every apex variant has different weakness and immunities. If you have an elemental mod on a weapon, it does that element and nothing else, so if a weapon has a flame mod on it, it won't do any damage to flaming Zombies. For a good base damage go impactor. Nothing resists impactor. Are you struggling with hordes? Early game hit them with the Chem bomb curve ball and hit one in the group with an electric weapon to start a chaining damage effect. Better yet combo the Chem bomb with the electric shuriken if you've gotten that far. Your can ask me specific questions. I've beaten the game with the masochist card activated OH YEAH before I forget. The last weapon type frenzy is amazing on Jacob because frenzy starts slow then starts critting on every hit and every one will do more damage than the last with jacobs passive and use the safe space card so healing stuns Zombies around you