should i say, COWARD or INCOMPETENT?
Yes.
But yeah, in my mind, it's pretty clear. Both are sentenced to death for the attempted murder, and the obvious kidnapping of Lady that will ensues, as well as the blackmail "We have Gray, if you follow us and marry me I won't kill him".
So yeah, no honor, no skills. He's so "powerful" and "skilled" he needed two people, poison and an abuse of power/blackmail to "take care" of a commoner... He's gonna be so laughed at in noble's circle... If he survives. Which he won't.