The drill

[Nike-it]

Originally Posted by BB Shockwave

This bugged me as well, and it'd be important to know, since the Drill is one of the permanent magic items (you can always buy it from the Chief Engineer, it is not random).

I did not use it as I had only one troop with Physical damage, but I could use it for my undead army in my next game.

It means, that these bonuses are given only to the troops with melee attack. Here is the list of such units: Archdemon, Barbarian, Berserk, Black Knight, Knight, Demoness, Dwarf, Ent, Ancient Ent, Swordsman, Guardsman, Peasant, Robber, Marauder, Horseman, Werewolf Elf, Miner, Giant, Goblin, Furious Goblin, Orc, Veteran Orc, Skeleton, Zombie, Decaying Zombie, Ghost, Cursed Ghost, Vampire, Ancient Vampire, Ogre, Shaman, Pirat, Sea Dog.