It is scarce but not extremely rare. GTR's signature is more rare on blades. Of course the most well known is on the 50th commemorative. I have Bo's "twice" on mine. He was quite special to me.
Pete Hamilton had both GTR's and Bo's signatures reproduced on templates for his panagraph machine. Unique, indeed and not often found on a standard, bare bones Model #1-7".
Hey...If it's a cool enough knife to be featured on the front page of the Randall catalog for years, it's cool enough for Bo's "autograph" also!
Below are a couple of photos of my commerative...and sheath.
Best, Capt. Chris