Our family (Sweatman) emanated from the City of Oxford in England where we have two records from the Doomsday Book of families living in 'hovels' or 'holes in the wall'. They were 'Moneyers' and were licensed to produce coin of the realm. Six coins (William I Silver Pennies 1066 - 1087) reside on display in the Ashmolean Museum in Oxford that have the name S?ETMAN stamped on the reverse.
We also have one of these silver coins which obviously, is very much treasured !
The 'A' in the name of Sweatman is an option that developed much later on.
The 'W' within the name is represented by a letter (?) that looks very similar to a p but is narrower and the curved part descends at 45° to meet the descending stroke and named (wynn, win or wen) and is descended from a Saxon 'runic' letter.