No torch or welder? Pound on it a little,then try to tighten it with the Vise Grips. If you can move it in either direction the slightest bit, you'll be able to back it out by working back and forth in increasing arcs and lots of oil. When that doesn't work, Plan B is to cut or grind the bolt down to about 1/8 above arm and start drilling. Start with a 1/8, then a 3/16, 1/4 or better a 9/32. Then with a blunt screw driver push the remnants in the hole you've created. Clean debris out with needle nose pliers. Plan C is an EZ out
Got it! The propane torch got it red hot. Then used more PB blaster, and vice grips with the jack handle on them to turn it out. And some help from the ol BFH.