>>223404small stone, like the one you mentioned seems preferred to me. Plus, I can sharpen an axe with it also... I think so anyways.
Why couldn't you strop a scandi with your belt? Ray Mears et al. seem to do this.
1)
http://www.youtube.com/watch?v=Lm53mCOQTR82)
http://www.youtube.com/watch?v=D4y8u_iJf1M3) axe
http://www.youtube.com/watch?v=GfY8HY50dGU