Erin almost, almost sends 'good job', and then she reconsiders it. Dimitri is a kind soul. Struggling to become something new he can't even imagine. He doesn't need affirmation that he can kill with skill, especially not when he seems so painfully aware of that awe-inspiring strength of his.

So what gets sent instead is:

You have done Giles an incredible kindness. Thank you for that. I am sure he will find a way to express his gratitude whenever he is feeling equal to leaving his home.