more of a question 4 chie bukuro but where does wo meaning although come from as in: 足元が 悪い 中を 頑張って、やっとの 思いで 会場にたどり 着いた。
It was very treacherous to walk and I struggled to get there, but finally reached the meeting place.

Isn't that just the regular を object marker, marking the object of 頑張る?
仕事を頑張る
自炊を頑張る
etc

yeah sorry I misinterpreted it - what about mono o although then?

を had a much wider range of meaning in classical Japanese than it does in modern -- in addition to the modern meanings, it could indicate "although" or "and" and go at the end of a sentence for emphasis. I believe the way it was explained to me was that it showed someone's emotional response to the given situation before.

In modern Japanese the meaning only survives in some set expressions like ものを.

I don't know more about the etymology of を.

thanks ydtt