Tolkien vocabulary I (serious)

[The Squatter of Amon Rûdh]

He's also been known to use 'fell' in the sense of a pelt or hide, as in Bombadil Goes Boating ("'I'll give your otter-fell to Barrow-wights. They'll taw you!'") and in the Lay of Leithian, where he wrote:

His dreadful counsel then they took,
and their own gracious forms forsook;
in werewolf fell and batlike wing
prepared to robe them, shuddering.

The first quotation raises another question: what does 'taw' mean? My Concise Oxford has "Make (hide) into leather without use of tannin, esp. by soaking in solution of alum and salt." A dire threat indeed!