There appear to be two distinct families of UK Bendings, one of Norman origin, possibly becoming extinct in the 19C, and the other originating in Devon and first recorded in the 16C, and there are families of Bendings in Germany, some of whom emigrated to the US (from Hesse Darmstadt in the early 1800s). I am not aware of any link between the UK and the German families.
There are a number of alternative spellings, Bendeng, Bendenges, Bendynges, Benynges, and others, which in this work have been shown as Bending.
W. S. Ellis, in the Herald and Genealogist, suggests that Bendenges is probably a corrupted form of an English local word, and that it has no analogy with any Norman name.
Clement Bending in his article on early Bendings (p. 18), states that Bending is derived from a manor held by the family in the twelfth century, but gives no evidence. In a letter dated 20/9/1965 he says that the area around Farnham in Surrey was known to the Saxons as Bendingas, probably the place of the people of Benda, and this is supported by the Ordnance Survey map of Britain in the Dark Ages, which shows Bintungas (120k) as a named place about 3 miles east of Farnham. This place is about 10 miles from Odiham and Hartley Wintney which have strong connections with the Norman Bendings.
Clement's reasons for stating that Stephen de Bending was a son of William de Windsor are not known but possibly because Winchfield once held by William had by 1166 passed to Stephen and in 1242/3 Sarra de Bending had a holding in Hardmead, Bucks, from William de Windsor, and in 1284-6 William de Bending had the same holding from Richard de Windsor. Winchfield and Hardmead were originally held by Walter fitz Other. (see History of Hampshire)
Clement argues that the DNB William de Bending was the son of Stephen, and was also known as William fitz Stephen, who is shown separately in the DNB, giving as reasons that their fathers were Stephens, were judges, and died about the same time.
Vasari in his The Lives of the Painters refers to the medieval Florentine painter Giotto as Giotto di Bondone, and Clement seeks to connect the Norman Bendings through the de Windsors and Others to the Gherardini of Florence. ( Lisa di Gherardini of Florence is thought to be the subject of da Vincis' Mona Lisa.) Perhaps Bending originated in Florence, but this is very unlikely, and even more improbable, after J H Round's destruction of the connection between the Gherardini and the FitzGeralds in The Ancestor (1902).
The name is possibly derived from Bindon near Axmouth. In the Anglo-Saxon Chronicle this is known as Beandune (70k), the site of a battle in AD 614 when two thousand and sixty five Welsh were slain. Even as late as the 1881 census there is a cluster of Bendings close to Bindon. (see Bending 1881 distribution)
In the 1238 Crown Pleas of the Devon Eyre, Axmouth Hundred, Robert de Bendone was outlawed for murder, and the fugitive's lord was Philip de Bendone. The de Bendone probably refers to Bindon, and although Robert and Philip share this description, it is unlikely that they were of the same family.
The surname of Sir Robert Bendyn, the King's admiral who had associations with Exeter, is possibly derived from Bindon, as are the sixteenth century Bendings of Payhembury and Honiton, the progenitors of modern Bendings. But this may only mean that Bendyn and Bending had origins in the same locality.
(see also Medieval Origins