it's not about threat, it's about them accepting what we are saying. if the Ishari are along they become part of our revelation reveal about the nature of the three curses and proving they exist, which the antagonized conservatives will push back against harder because of.
I don't think there is an over the top when your trying to get the acknowledgement of your entire, slightly backwards do to Nurgle mindwhammy race for the sake of saving their very souls. your worried about provoking envy and sacrificing the chance to inspire awe in the process. a crone sword class vessel is the kind of thing to draw out Aeldari superstition and premonitions of victory.
That saying you quoted by Teddy Roosevelt? your supposed to have the stick with you to discourage violence, not hide it away to surprise someone with because your worried their is a chance things go south. a deterrent needs to be seen to have value as a deterrent.