Re: splinters and dents in bokken
Just sand it out so that there isn't a new place to start a splinter (ie sand out all of the cracks, and make everything pointy nice and smooth). Filling back in rarely works as the filler tends to just pop out again. The finish I like to use is 2 parts linseed oil to two parts tung oil to one part beeswax, heat it gently until the beeswax melts and you can mix it all together, then rub it in with a rag with enough friction to keep everything warm and work it well into the wood.
Hope this helps,