This build for fist weapons/TM got me through most of the content on normal; I blueprinted it using the sheepherder fist build posted prior; the key differences being this will NOT work for totally unarmed and is poorly optimized.
https://underrail.info/build/?Hg0LBwMEAwUAPADCoCgKwqAfKB8APHM2QWYAwpsAcAAAVSsmMWkgBkMWB0sDEww8woXCtnzCh-KdjQrinZcC4qe-A9-_Some takeaways:
-Nimble is likely a better choice than BWT, only took it near the end since I was using Aran's armor and didnt really like any of the other vet feats after In.Str.
-Mechanics is low b/c I relied on The Claw + Power Fist rather than crafted gloves, and didnt use any metal armors or bladed gear (this is also the reason I didnt prioritize TfB). Power fist is crucial in this build for robots and crabs.
-Fist damage scales very well with Str so you'll want to pump that and keep Dex as your second-highest stat
-Pickpocketting was a waste of points here, I'd either redistribute those to the psi schools or to traps
-Blindsiding felt a lot more effective than I imagined it would after I took it, so I'd move that up in priority a little. In contrast, I'm not sure how effective deflection ended up being so I'd swap that out for Escape Artist. Also, fancy footwork should be much earlier, probably swapped with where grenadier currently is.
Hopefully this helps; fist builds are quite a bit of fun in this game once you get your damage on-line.