The main reason scandinavian knives don't have guards is that the guard gets in the way for carving, wood working, and bush craft. The second is that they're not a fighting knife and not really intended for one handed stabbing (if you need to, you use two with one on the pommel and there is little risk unless you're over-doing it).

Nearly all of the 'cheap' Frosts knives I see locally have a small plastic guard as part of the handle. It's shape leads me to believe that it's only purpose is to keep hands from slipping onto the blade. But since this $9 knife is a common one for boys to get a start with...typically at scouts or a similar organization, I imagine that marketing works for them here in North America.

I've used many wooden and plastic handled Mora's over the years...with and without guards. I've never had one slip in that way (I HAVE cut myself many times on them but not since I was a teenager). If wet or frozen I could see some risk but when the risk goes up that just means there is more responsibility on the users part to be mindful of the limitations due to the conditions. I think it's been said many times here that any knife will do it's job if you don't ask of it more than it was designed to provide or use it in a way it wasn't designed to be used...handle design isn't exempt from that rule.

My new JA Puukko has a wooden handle with no guard and it's as solid as a rock in my hand. Part of that is due to the fact that it's not painted or varnished. The real wood texture is better than any rubber knife handle.