The Emperor exclaims "Too deceitful! Too deceitfull!!!" in response to the "gift" (dead body of one of his territory lords) and the message from MC about his promise to return and invade their kingdom (in retaliation for the overt - in broad daylight - attempt to murder him and his entourage by surrounding and ambushing them) once the turnnament is over.

What could possibly be considered "deceitful" about MC's gift and message to the Emperor? It seemed 100% straightforward to me, if very blunt. It even seemed warranted, given the circumstances.
Rather, the Emperor exclaiming such a rediculous thing could not be more ironic, since it was them that acted very decietful in ambushing and trying to murder MC, especially since he's the royal heir from a neighboring kingdom just passing through, and doing this merely because they were jealous of his talent and afraid of how powerful he might become.
Perhaps the translator just messed up very badly and the phrase they were looking for was "How disgraceful"?

What could possibly be considered "deceitful" about MC's gift and message to the Emperor? It seemed 100% straightforward to me, if very blunt. It even seemed warranted, given the circumstances.
Rather, the Emperor exclaiming such a rediculous thing could not be more ironic, since it was them that acted very decietful in ambushing and trying to murder MC, especially since he's the royal heir from a neighboring kingdom just passing through, and doing this merely because they were jealous of his talent and afraid of how powerful he might become.
Perhaps the translator just messed up very badly and the phrase they were looking for was "How disgraceful"?