Hwætmann is an Old English masculine name formed from the elements hwæt, ‘sharp, bold, brave’, and mann, ‘man’. The first element is rarely found, but the second was a common suffix in names newly coined in the late Anglo-Saxon period (von Feilitzen 1937: 297, 324). Three or four other men called Hwætmann are currently recorded in PASE, and curiously they were all moneyers: at York in the period 979–85 (Hwætman 7), at Norwich under Æthelred II and Cnut, 1003–29 (Hwætman 5–6), and at the Dorset mints of Bridport and Dorchester under Harold I and Harthacnut, 1036–42 (Hwætman 2–4). The last may have been the same as the Hwætmann who struck at Bridport in the last years of Edward the Confessor and in the mid 1070s for William I (Hwætmann 1); such a long career is not entirely implausible, though it may be that we are dealing with two successive moneyers of the same name. No coins struck at Bridport between 1042 and 1065 are presently known, so that continuity between the moneyers at work in 1036–42 and 1065–6 cannot be proved or disproved (EMC).
EMC: On-line Early Medieval Corpus of Coin Finds/Sylloge of Coins of the British Isles http://www.fitzmuseum.cam.ac.uk/dept/coins/emc
von Feilitzen 1937: Olof von Feilitzen, The Pre-Conquest Personal Names of Domesday Book, Nomina Germanica 3 (Uppsala: Almqvist and Wiksells, 1937)
Spellings in Domesday Book: Wateman, Wetman
Forms in modern scholarship:
von Feilitzen head forms: Hwætmann
Phillimore edition: Hwætmann
Alecto edition: Hwætmann