You can create one character per server (so one on the War server and one on the Peace server) if you want to try out different character builds. You can also reset your character's stats using the plus (+) icon in the main action bar at the bottom of the screen. This way you can try out different stats without creating a new character.
The reason for one character per player (per server) is that each character is allocated physical space that can be claimed as tribe land, either as a separate homestead or as increased space in an existing tribe. I hope that helps players understand the reason behind this decision. (It was a standard choice for similar games when Xsyon was first launched).