I've made several BC bows one actually didn't break
The one that survived did develope many frets
which tells me I didn't have enough limb working. It is beautiful wood and very light in the hand. As for finish
I usually use Tru-Oil, but many things will work, shellac, spar urethane, varnish, poly, plain old parriffin wax,
animal fat like bear grease and so on. No finish is completely water proof but some are better than others.