Understanding “name of a person＋をして”

Question

何の躊躇いもなく晒された令音の裸体は、同性である琴里をして息を呑んでしまうほどに美しかった。

What is the usage of the bold part (i.e. name of a person＋をする)? Does it mean 琴里として?

Answer 1

That をして indicates the agent of a verb in a causative construction. It is an old form and should actually be paired with an old causative form, 〜しむ or 〜しめる. 琴里をして息を呑ましめる would mean the same as 琴里に息を呑ませる. In modern usage, it is often used with the normal causative form 〜せる, as in 琴里をして息を呑ませる, and somehow tends to carry a sense of emphasis as if the agent is hard to make perform the action of the verb. It’s like saying 琴里にさえ／すら息を呑ませる.

Now, in your example, the verb is not even causative. Though it seems a misuse to me, it still retains the emphasizing effect as the author probably intended. It’s like saying 琴里（で）さえ／すら息を呑んでしまう

This sense of emphasis may be because it is confused with を[以]{も}ってしても. I’m not sure.

Answer 2

(人)をして is an archaic or old-fashioned usage. According to the grammar of the old Japanese, as Chocolate clearly stated, it should be 琴音をして息を呑ましめる or 琴音をして息を呑ましむ just like this example.

彼をして走らしむ。（彼を走らせる。）

So it will be safe to say that this sentence is a strange combination of modern and archaic phrases. But to think of the author's intention of using the archaic phrase of (人)をして, the author, of whom I have no idea, must have wanted to make his or her work seem more historical or archaic by spotting archaic words or phrases here and there in mainly modern Japanese.