I am new to this forum as well, but not new to working with leather. I have made a lot of moccasins and medieval style/type shoes and a few boots (made a pair of cowboy boots with Jack Reed back in the 90's, and a couple pair after that but not any since - not any cowboy boots that is), and a lot of sandals too. So here is my 2 cents for what it's worth since no one has responded to your question. Leather is notoriously slippery in wet conditions no matter what. One thing that helps is to put the rough/flesh side out, but even that gets slippery too, and it doesn't take long for the flesh side to get kind of slicked down after wearing them for a little while. If you used "hair on" leather and put the hair to the ouside, this will give traction better than any other kind of leather, but eventually the hair wears off and you have to find another solution. Moccasins don't actually last that long in the wilderness. I have read many accounts of native peoples carrying more than one pair on a trip to replace the ones that wear out along the way. You could tool the leather, but I doubt that would really make much difference. I have just recently begun using old mountain bike tire tread to put on the bottom of some of my shoes/sandals. It works well as long as I use a wire brush and "rough up" the inner side of the tire so the contact cement will adhere to the rubber. If you can find a 29" fatty street style tread (heck you could even buy one brand new and cut it up for soles - they don't cost too much), that might give you more "feel" for the ground while hiking. Even the mountain bike tire tread is pretty thin and still allows for quite a bit of "feel" of the ground - as long as your leather sole isn't too thick. There are a good many solutions to this "problem". Some people take shredded/crumbly rubber from old tires and mix it with contact type adhesive and put it on the bottom of soft soled footwear - looks like crap, but it seems to work for them. I have never tried it. You also can get some thinner crepe sole material (your local shoe repair guy might sell you some, that is where I get mine - or you can order it from suppliers on the web) and glue it to the bottom of the moccasins. It should stay on as long as you get it secured well with the adhesive especially at the edges. Rubber tire inner tubes can also be glued to the sole too - they are relatively thin. Also vibram sells thin tough sole material that I have heard a lot of people like. I don't remember the exact name of it, but maybe someone else on here knows what it's called (they make a bunch of different kinds). As I recall it was one of the most expensive one's they make, but I read several rave reviews of the stuff by "minimalist" footwear runners on the web recently. Hope this helps some. (Vibram #7175 Cherry Slip-resistant rubber soling sheet)