Sextant -as I understand they are brass , so you could make yourself a knife out of it.
Learn firemaking using bow-drill, I leant it yesterday. But you will need some good tinder. I guess you could try put some fuel on some very rotten and very dry piece of wood and it should irnite. But read about bow drilling, I used Ray Mears' book, other sources did not give me enough information (but I am not native english speaker, so it was also difficult for me to understand)