I feel this to be a parade shield, something crafted for pure obstentation (Rituals? Games? Parades? Triumph processions?).
Too much detail, too much paint, too many figures.
Most of it will be gone after any simple one-vs-fight.
Have a better look at the shield.
There is not even a slashing or piercing sign.
It was not made for real combat.
Professional legionaries never had stuff like that on a battlefield.