Guiscard

I can't find any such ON word viskr - visk occurs only in the sense of wisp of straw, cognate with similar words throughout the Germanic languages referring to straws or bundles of straws/twigs (incl. English whisk). The word for "wise" is viss or vis- in compounds, so at best this is misanalysis and the c is part of the following element, (ch- for Germanic h- common in Latinised Germanic names in France.)

---

Further Wis- as a name element itself must be questioned - the older Indo-European element *h₁wésus. Occurring in a number of Germanic names as Wisu-/Wisa- (but also in Illyrian Vescleves, Celtic Sigovesus, Bellovesus, and Celtiberian Vesucloti) seems to have been assimilated to the more familiar wise (manner, way, but feminine), wis (certain, wise) or wisi (leader, a back-formation from wisijan, instruct, lead). Similarly Batic Wisuwalds and Slavic Vsevolod seem to have been assimilated to the more familiar Visas and Vse "whole, all" from Proto-Balto-Slavic *wiśas, from Proto-Indo-European *(h₁)wíḱwos. Cognate with Sanskrit विश्व (viśva).