Mangonels and bombard cannons have splash damage that hits everyone. Scorpions only hit enemy units.Yeah it sure is pretty punishing. Also im having a bit of trouble balancing my economy.
One more question, do siege weaoons etc cause friendly fire?
When rams are upgraded they do splash damage, but it's negligible to units.
Trebs do splash damage in theory, but it's negligible, unless it's Ethiopians with the unique tech researched.