When you get to a certain amount of allies/followers (or fame) you'll unlock the stables and the merchant
use the facility materials to upgrade both (trade in weapon material for facility material to make it faster), go to the stables and feed the animals until a message says that an animal has reached its max and is satisfied, you'll get a either a weapon, materials or a new animal (unlocked) or any combination of the three, the new animal should be able to be purchased from the merchant
The other step is to level up the barracks, the higher the level, the more chance you'll get of getting things besides facility/weapon materials
When you get to a certain amount of allies/followers (or fame) you'll unlock the stables and the merchant
use the facility materials to upgrade both (trade in weapon material for facility material to make it faster), go to the stables and feed the animals until a message says that an animal has reached its max and is satisfied, you'll get a either a weapon, materials or a new animal (unlocked) or any combination of the three, the new animal should be able to be purchased from the merchant
The other step is to level up the barracks, the higher the level, the more chance you'll get of getting things besides facility/weapon materials