Originally the Decani were a unit of the pre-kingdom Atlantean city states, they were armed as heavy shock infantry designed to soak attacks before retreat allowing the Roarari, Losantes, and Andabatae to fight more effectively. After the kingdom era, and the Atlantean military was reformed, the Losantes were retired, Rorarii became light reserve infantry, and Andabatae were used to fulfill the void of the Evocati.

As technology, metalworking, and armour-making improved during the years of Atlantis, plate armour would eventually be developed, however plate armour was expensive, and only fielded by Royal Guards, Legionanires and Dominates. as did the weapons needed to penetrate them. Weapons such as crossbows, polearms, and even maces could be extremely effective vs plate armoured soldiers of rebellious colonies. The most effective of these anti-armour weapons was the Warhammer, now wielded by the reformed Decani. Decani are extremely strong and bulky men, armed well in strong armour, but their warhammers make them only effective against highly armored opponents.