V-ている方が meaning

Question

遠坂はしゃがみ込んで、倒れた女生徒を介抱している。
その横顔は真剣そのものだ。
額に汗を浮かばせながら、女生徒の安否を気遣う。
…なんだろう。
その、見ている方が痛みを覚えるほどの真剣な顔を、俺は。
つい最近、すごく間近で見た覚えが---

Tohsaka squats down and start to look after the collapsed student.
Her face looks serious.
While sweat is dripping down her forehead she starts to worry about the student's wellbeing.
What's this?

And I can't understand the last part

My translation would be:

"Rather than seeing it, I would rather feel it", this serious face, I.
Not too long ago, I have a memory of it.

Is 見ている方が used with the meaning of 見た方が?
Is it used like this because she is doing doing the action of seeing right now?

Edit: Upon re-reading how 方が works my new translation would be.

That, "Looking is more painful" serious face, I.
Not too long ago, I have a memory of it.

Answer 1

「[方]{ほう}」 has several different meanings and it seems that you are trying to apply one meaning of it to the 「方」 in this context where it is used for another.

To be more specific, you are clearly thinking of the "comaparison 方" as in "A rather than B", are you not?

In this context, 「方」 is used to mean "the side" as in doers vs. on-lookers. Tousaka is working hard to help the girl. He is on the "doing-the-job side" -- 「している方」.

「見ている方」 means the (imaginary) persons (possibly including the narrator) who are just watching Tousaka helping the girl. In other words, it refers to the persons who are on the opposite side from Tousaka regarding the event currently happening.

Read the 2nd, 3rd and 4th example sentences in Definition #4 in goo[辞書]{じしょ}

私の[方]{ほう}の[手落]{てお}ちでした The fault was mine.

[彼]{かれ}の[方]{ほう}に[不服]{ふふく}はなかった There was no dissatisfaction on his part.

私たちは[皆彼]{みなかれ}の[方]{ほう}についた All of us sided with him.

This usage of 「[方]{ほう}」 is very common among us native speakers. (And I have personally seen J-learners getting this mixed up with 「[方]{かた}」 countless times, but I will not get into that here.)

「見ている[方]{ほう}が[痛]{いた}みを[覚]{おぼ}えるほどの[真剣]{しんけん}な[顔]{かお}」

therefore means:

"the serious-looking face that is enough to make the on-lookers actually feel the pain"