I have always liked he Hall wrenches and they come in a wide range of sizes. The smallest is a bicycle wrench about 5-1/2" and the largest 48" if I remember correctly. They were for both nuts and pipe. The "keep sharp' refers to the inside edge of the lower jaw. Below is an add from the League of American Wheelmen and Good Roads Bulletin - 1897 shown on DATAMP.
(http://www.datamp.org/images/20069-3.jpg)
There is a variant of the smallest one on the auction at York NE this weekend.
0376. HALL WRENCH / PAT'D MAR. 13, 1894 - - 5.5" comb nut and pipe center screw adjust with a pivoting top jaw. The flat sides of the jaws were used for nuts and the sharp back bottom jaw edge for pipe. Patented by Charles Hall of New York, NY and mfg. by Samuel Hall's Sons of New York. Good+. (S1081, C155)
(http://i222.photobucket.com/albums/dd3/buswrench/shockman-2013/Y13-363-376_zps873bc1b5.jpg)