In terms of fighting ability the Blacksmith is considered their upgrade.
Merchants are a very gimmicky unit, having the ability to summon shops outside of battle. In battle, they give mediocre defences and a large TEC bonus to their teammates with their stat distribution. They have a fairly small skillset and can have trouble finding a place on teams at late game or New Game+.
|Level learned||Skill name|
|Level 4||Armor Break|
|Level 8||Summon Shop|
|Level 16||Gran Chain|