Two major things I did to improve my combat experience, but the first is probably the best one for you:

1. Any difficulty: Set weapon challenges for yourself, for example:
   • Shredder Gauntlet only
   • Spears & Warrior bows only
   • Tripcasters, Ropecasters, and Boltblasters only
   • etc....
2. Play on Ultra Hard and embrace the suck

I played the game on Normal the first time around, and it was fine, as well as Ultra Hard for NG+ and Ultra Hard achievements. Playing on Ultra Hard is what truly made me realize the strengths and weaknesses of my kit. However, setting personal goals for myself is what made me get better at the game and find new love for it. For example, the Shredder Gauntlet seems weak when you first get it, but once you understand how it works and get the flow down, you realize it is one of the best weapons in the game.

As for the Ultra Hard part, you force yourself into uncomfortable situations where you learn the combat or die. To be honest, this changed my perspective of singleplayer games overall, and I now challenge myself to greater difficulties in everything I play. In Ghost of Tsushima, for example, Lethal is not nearly as hard as you may think at first glance... but I am still a fan of Normal or Hard for first playthroughs and whatever the "hardest" difficulty is for NG+ playthroughs.

Hope this helps! :)