I used the starting club for the first 1-14 levels I think, then I think your fist become better. Then at 20 but I was able to buy two
Wu's Trance Stick which are better than your fist at this level. The "sticks" are sold pretty cheap and you can probably get one under 100p. Someone was nice to me and gave me 2 for 100p.
I also rotated using club/fist to keep my skills maxed in both. The first link I posted will have your fist damage based on level. Also, you may want to look at damage caps per level ranges:
Damage Cap
Damage cap = (dmg * 2) where dmg is the weapon's stated damage.
levels 1-9 - damage cap is 20
levels 10-19 - damage cap is 28
Levels 20-29 - damage cap is 60
30+ - lifted, can do 2x weapon damage or more based on class
The dmg*2 formula is true until lvl 28 where you get 1 bonus damage every 3 levels to your main hand attack. So at level 50 you get 8 extra bonus damage:
main hand = (dmg*2)+8
off hand = dmg*2
That's why a fast weapon can perform as good as a slower weapon with better ratio. For example, a dragon spined claw (10/21) only outdamages a revultant whip (5/14) by about 10% or maybe a bit more (that's my personal parse). For off hand, you need the best possible ratio (no damage bonus).