Mercenary suits (including the bandit version) are armor thats already worn and thus you can wear armor over them for added protection. The mercenary suits just like the sunrise suits only provide damage protection nothing else. As for the beril suits they are not the best suits but not completely useless as you read below.

Bandit mercenary suit: Health 165, hunger 165, sanity 200. Damage absorption: 30%.

Mercenary suit: Health 165, hunger 165, sanity 200. Damage absorption: 30%.

Military beril: Health 170, hunger 170, sanity 200. Armor protection 50%, durabiltity: 800, small insulation for the summers and winters, medium rain protection, lighting protection, sandstorm protection, and included nightvision.

Freedom beril: Health 170, hunger 170, sanity 200. Armor protection 50%, durabiltity: 800, small insulation for the summers and winters, medium rain protection, lighting protection, sandstorm protection, radiation protection and included nightvision. Perk: Move 20% faster when health is over 90%, Move 15% faster when health is at 70%, move at 10% (regular speed) at below 70%.


Spawncodes:
Military_beril
Freedom_beril