Bleach and fix vs. Farmer's reducer

I want to try to reduce the highlights on some prints and I don't understand exactly when to use these two techniques. I understand from Anchell's Darkroom Cookbook that the ratio of A and B solution in Farmer's is for local or overall reduction and as I said I'm looking to affect only the highlights. When would I use a bleach and fix method vs. Farmer's reducer.

Part two of the question is how will these affect Selinium and Gold toning on Ilford WTFB?

Thanks for your help,
James