It seems like the general idea is that a few of the feats are meant to be your big damage upgrades. For instance, under General Feats there's Attack Specialist/Veteran/Ace which have you roll double/triple/quadrupal damage die, respectively. There are also various Combat Feats that add the Tension Die to your damage roll, but that would often only be a d6 or d8. I assume they could stack though.
You can also upgrade weapons with modifications, but off the top of my head I don't remember if those add damage or do other things. But my guess is the design philosophy is to not focus on combat quite as much, so there don't need to be a hundred different ways to increase your damage. A few more would be nice though.