| โ | All Mercenaries gain custom weapons. Mercenary attack increased. But, all your buildings now cost significantly more to construct. | โ |
| —In-game description | ||
Customized Merc Weapons is a technology in Age of Empires III that is unique to the John Black's Mercenaries in Act II: Ice and can be researched at the Church once the Fortress Age is reached and the Royal Decree to Claim the New World Home City Card has been sent. Once researched, it increases the damage of mercenaries by 30%, but increases the cost of buildings by 30%.