Torso of Legion
From The Heroes of Might and Magic III wiki
|Torso of Legion|
|Effect: This item, when equipped by a hero in a town, increases the growth of 4th level units (in that town) by 3 per week.|
Increases your Town's Level 4 creature production by +3. Your hero have to equip it and be in Town (visiting or garrison) for the bonus to work.