This is how I fixed my leather boots.
I hope they are going to last me for way longer now, because I really like them…
I'm wearing them from quite a while now and seam this method worked really well.
Step 1: WHAT YOU NEED
-waterproof leather glue, a good brand that dry flexible and clear,
-a scrap piece of nice leather of the same color (or not!) of your boots,
-(a pair of holed boots).
Step 2: CLEAN THE BOOTS
Clean your boots really well around the broken part.
Allow to dry completely.
Step 3: ROUGH THE SURFACE
With the sand paper rough the surface of your boots around the holes, only and everywhere under where you are going to patch them, from one side to the other of your boot.
Step 4: CUT a STRIPE OF LEATHER
Place the leather on top of your boots and cut a stripe that cover the holes, going from one side of the other of your boots.
Step 5: PUT THE GLUE
Put the glue allover the behind of the leather stripe you cut.
Spread it really well and deep everywhere, especially on the edges.
Step 6: PLACE THE STRIP
Place the strip and clean off the left over glue.
Press hard on the strip everywhere, placing one hand inside of the boot. I did this operation for few minutes on each boot, to make sure the leather strip was stick really well on the boot.
Step 7: DONE!
Done, let them dry over a night or until your leather glue need.
The stripe is noticeable, but I don't think it look so bad!
Now you can polish them and make them look nice whit a bees wax lotion: https://www.instructables.com/id/BEES-WAX-LOTION-for-hands-boots-and-wood/