A couple weeks back Jeff asked me to post a video of me forging a rat tail. I do not have a video but I did think to snap a couple pictures on the last one.
In this picture I just cut into the handle end from the direction opposite the rat tail. In this case the top of the handle is cut downward leaving enough meat to allow the rounding of that sharp "V" (very important)and to remain strong enough to hold a lanyard.
In the above picture I have made the cut and folded the tail down and bobbed off the corner of what was the square bar. That corner will cause you problems if you leave it.
Then I re heat and lay the "V" down onto the top corner of the anvil and just work the tail out a little leaving it blunt. I wait to draw it to a point till I get the taper drawn into the full tang. Right now, it is thick and will withstand heat better and stuck outward and out of the way.
In the next picture the tang has been tapered and I start the curl. Here I see that I want to do some refining of the tail so I leave it opened up so I can access it with a file.
I file it till I am happy with it then close it up. I actually went back and refined it more after heat treat. I used a chainsaw files and needle files.