Fogsvans is 'handsaw'. The word is borrowed from German Fuchsschwanz, literally ‘foxtail’, because of the shape of the tool.
Fuchs and fox go back to the Germanic root *fuh and further back Indoeuropean *puk-, ‘tail’. Swedish has has also borrowed the word Fuchs, spelled Fux, meaning a bay or sorrel horse, or a nightfly. The Swedish word for fox, räv probably means reddish brown.
Schwanz is ‘tail’or ‘train on a ball gown’, from the Middle High German verb schwanzen, ‘to swing back and forth’, from Germanic *swangatjan (English swank), an iterative or intensitive variation of *swenganan ‘to swing’.