rawhide shoe lace cutting tool & mystery tool

The small tool in the photo was used to make rawhide shoe laces. While holding the tool by your index finger and setting the width of cut, you can strip a strand off of a sheet of rawhide. The rawhide is held in one hand, and the tool in the other hand. By slicing the blade along the edge of the rawhide, you slice a strip that is thin enough and strong enough to make a shoe lace. I've seen these tools as they were once displayed on the hardware store shelf . They were stapled to a piece of cardboard stating how to use it. The price on the cardboard was 5 cents.
The second and larger tool, I purchased at an auction. It is very similar to the lacing cutter but has different features. It must have been used for something special. I have been trying to find out it's use since I bought it. It has a long steel tube that is cut at an angle and is very sharp. Along this tubing, close to the base, is an elongated slot that obviously had a purpose for it's use. I thought that it maybe, might have been used to make fly nets for work horses in the field, but, I don't know.
I need your help on this one folks. Help me find the purpose of this tool. It's driving me crazy. .....hotairfan