Oh, green fellow, my 'pointy head' has a price you may not afford, but we may have some fun bargaining.

I'm honored in a way by your attention, alien, it's impressive that even the mind of a crude genetically constructed brute may appreciate the Eldar art. Still, when the War God Khaine leads us to battle, there will be no mercy on that path.
(Thanks, it's a nice thing to hear. And yes, the design for the Eldar is just one of a kind)

Thank you, Inquisitor. And don't worry, if I see other Inquisitors I don't speak, my sword does)

Thank you, my swooping friend, you may count on my aid from the ground.

Thank you, a greeting from an enemy is already a sign of a glorious battle to come!