Sometimes mechanics need specialty wrenches that are not available from Snap-on, MAC, Craftsmen, etc.
In the Aircraft maintenance industry, this is a common thing.
This modification even had a engineering drawing with it.
I used Hastelloy W filler rod because I have had success with it many many times when modifying a wrench like this.
In this video, you will see the importance of cleaning mill scale along with several other tips for tig welding steel
Modifying Wrenches is common practice in certain industries like aviation maintenance. There are tight areas where a conventional wrench wont fit.
Hastelloy W is usually a great choice when you know its steel but cannot determine the exact metal type.
TIg welding box cutter blades can be very good practice because it makes you get used to focusing your eyes on a very small puddle, you have to get used to using a very small filler wire, and you also see how beneficial it is to use aluminum backing on thin metal.