Physical attack bonus applying separately to all types of attack?

Hey, is it WAD that physical attack boni apply separately, indiscriminately and quite bountifully to each type of attack? My henchman Warrior (+3) has three Lethal abilities (+12) and additional banner bonus from a friendly Commander (+1), for a total of +16 attack bonus. I equipped him with a melee weapon and three trinkets adding +1 different elemental damage type each. The calculation is:

Weapon: 16 base attack + 16 bonus

Fire: 1 base + 16 bonus

Cold: 1 + 16

Lightning: 1 + 16

Total: 83 attack damage

I definitely like the damage output, but is that really intended?