If you check the history of Friesans in the US during the time Figure was born, you would find they were not present. They had been imported in the 1600's, because they were quite common in European countries. But they quickly died out in north America as a "breed" because they were crossed so many times with other breeds that were present here. So any Friesan blood by mid-1700's was likely very, very diluted. Probably enough so that it couldn't be a major factor. Arabs, however, were on the up-swing in the US during the time Figure was conceived. They were gaining in popularity like wildfire and infiltrating the East Coast. The Arabs of olden days did not look exactly like the modern Arabs, much like some lines of modern Morgans do not very closely resemble Figure's conformation. Eighteenth century Morgans looked quite similar to 18th century Arabs.
There is actually nothing proving that Figure was the result of purebred x purebred. We have names, and descriptions, but not breeds. So he was very likely a Heinz 57 mix. My vote is a regional draft with a high percentage Arab influence or fairly close in the line. Probably some gaited blood of some sort and colonial throughbred, too. Like I said, Heinz 57, that just happened by the grace of God to be extremely potent at passing his traits on to whatever mare he was bred to.