What does をし mean in this sentence


I was reading a web novel when I came across this sentence.

> 春を思わせる花柄のワンピースに黄色のカーデガン、編み込みをしアップにした髪にベレー帽、赤色の伊達メガネ……

What does the をし mean? Is it just connecting 編み込み and アップ to にした? It is my
first time I believe encountering this and while I still understand the
sentence I want clarification.

I looked online and all I could find was をし being a old way to write 惜しい and
愛しい which I am near certain is not how it is being used here, because that
would be quite bizarre and doesn't really make sense.




The only possible interpretation for me is that し is the stem of the ます-form
of the verb する.

I think the author meant both 編み込みをした (braided) and アップにした (put up) to modify
髪. It basically means the same as

> 編み込みをして（、）アップにした髪

I guess the author wanted to avoid repeating 〜して and 〜した because it would
sound a bit like the two actions, 編み込みにする and アップにする, happened sequentially in
time.

I would say the sentence is still poorly formed, though.

> 編み込んでアップにした髪

would have been much easier to understand. Here, the verb 編み込む is used in its
て-form, instead of 編み込みをする, where 編み込み is a noun and the object of the verb
する.

