Why leather armor for a rabbit? Well, a rabbit's key ability is dexterity. Although mail and plate armor may raise a rabbit's armor class, it can also induce a dexterity penalty and cause encumbrance problems if your dungeon master is a stickler for those rules.
So it's best to keep to leather armor or magical armor options for when you must take your rabbit adventuring. Etsy seller The King's Shilling can properly equip you and your furry pal.
-via Technabob