fighting ship
艨 centers on a large, armored warship used in battle. The single meaning 'fighting ship' captures this specialized vessel.
艨 combines 舟 (boat) with 蒙, which likely contributes the sound. The character is a phono-semantic compound for a type of warship.
The left side 舟 is a boat, and the right side 蒙 looks like a covered, complex structure. Picture a heavily armored fighting ship with a covered deck and hidden weapons.
For モウ, imagine mowing down enemy ships with your fighting ship: mow -> モウ, as the warship cuts through the fleet.
warship