1) The ‘foin’ was an animal of the marten kind, called the stone marten by Veale, and its fur was popular from the late Middle Ages.
In Yorkshire, the usual spelling was ‘foynes’, in the plural, and it generally referred to fur used to trim or line garments, especially men’s gowns: 1392 unam togam ... furratam cum foygnes, Swinton in Ryedale
1441 Roberto Thornton meam nigram togam furratam cum foynes, Oswaldkirk
1529 my blak velved gown furred with foynes, Featherstone
1561 my best gowne lyned with foynes, Leeds
1680 ‘The Mayor shall have and wear in his best gown a fayce of furr called foymes [sic]’, Beverley.
2) A thrust with a pointed weapon, used also as a verb.
There is evidence for both in the account of an affray at York Minster gate: 1490 William with a fone of his ax hurt the said Thomas
when thai were without apon the Cite ground they turnyd ayane … and fonyd inward with the poynts of ther axes.