Nevermind, Danth is correct for 1h weapons at least, the main hand damage bonus looks like it is just getting added on at the end as a flat number.
My 58 Shadowknight is hitting for 132 max with
https://wiki.project1999.com/Eye_of_the_Rigtorgn . He has 226 STR and 220 Offense. He also has 2 Aura of Battle items + Grim Aura. So 226 + 220 + Attack bonuses? ~40 = 4.86 x 25 Weapon Damage + 11 = 132 rounded down.