For me, for jams, unless I need a really really specific sound effect, I just go with music or sound packs. I'm honestly pretty new to making sounds, so I just use Audacity and a mic. For example, in Leafsticuffs the sound Leaf makes when he lands a punch is actually me hitting a garbage bag.
Cafofo has some great sounds in the Medieval Combat Sounds pack that might work for a game like yours!