Melee Damage
Each point of ST give +1 to melee damage.
It's not big bonus in the end.
1ST = 1 Melee Damage
2ST = 2 Melee Damage
3ST = 3 Melee Damage
4ST = 4 Melee Damage
5ST = 5 Melee Damage
6ST = 6 Melee Damage
7ST = 7 Melee Damage
8ST = 8 Melee Damage
9ST = 9 Melee Damage
10ST = 10 Melee Damage
Bruiser
+4ST, -2AP and doubles Melee Damage.
(Can choose only up to 6ST)
Melee Weapons (+ Unarmed weapons)
Every weapon has change to KD, without Heavy Handed trait and depends on your ST.
If you have Heavy Handed, this would not affect better to your KD changes.
Under than 5ST -> 2% change to KD
5ST = 2-4% change to KD
6ST = 4-6% change to KD
7ST = 6-8% change to KD
8ST = 8-10% change to KD
9ST = 10-12% change to KD
10ST = 12-14% change to KD
Edit: Bruiser maybe work like that already, just wanted to be sure.