meaning of 最初にして最後の見せ場


Context: the boy has just died while saving a girl and is now in the
afterlife.

> 「……あの女の子は。……俺が突き飛ばした女の子は、生きてますか？」" 大切な事だった。 俺の人生で、 **最初にして最後** の見せ場だったのだ。
> 命懸けで助けに入って、結局間に合わなかったのだとしたら悔し過ぎる"

It has been translated as:

> That girl … the one I pushed out of the way. Is she alive ?” That was
> important to me. It was the first - and last cool thing I’d done in my life.
> If it turned out I’d been too late, that I hadn’t saved her - that would be
> awful.

Could you explain what 最初にして最後 means ? If if translate with my own words, does
it mean: "I was a good actor from beginning to end" I'm not sure .




X にして Y is a bookish conjunctive phrase roughly translatable into "X as well
as Y", but also carries a certain rhetorical factor, that describes that Y is
supplemental but by no means less important. In this sense, I think the
translation you found does a fairly good job utilizing a dash.

> 俺の人生で、最初にして最後の見せ場だったのだ。  
>  (As) it was the first—and the last—high point of my life.




I'm afraid that it is not translated to "I was a good actor from beginning to
end". It means that was his first time to do something he could be proud of,
but at the same time it was his last time to do that because he died.

