Equipment

client.equipment.get_inventory() lists the items no commander or castellan is wearing:

inventory = client.equipment.get_inventory()
for item in inventory:
    print(item.equipment_id, item.slot, item.rarity_id)

Equip and unequip

commander = client.commanders.get_commanders()[0]
item = inventory[0]

client.equipment.equip(item.equipment_id, commander.commander_id)
client.equipment.unequip(item.equipment_id, commander.commander_id)

Both return False when the server refuses the move. Their replies carry no data, so read client.commanders.get_all() again to see the change. To move an item from one wearer to another, do as the game client does: take it off the first, then put it on the second.

What a commander already wears is on Commander.equipment; see Commanders.

API: EquipmentService, Equipment