I make a lot of shaving brushes, and try to avoid wood as much as I can. The preference is either resin stabilized wood, or resins. River Ridge does a good job on stabilizing wood.
But, from time to time, I make a wooden brush and finish it as follows:
soak the finish turned and sanded handle in "Bush Oil" for 3-4 days, then let dry for 2-3 days and then I apply many coats of Minwax wipe-on finish. About 10-14 coats, twice a day a coat. Dry for three days and then buff.
Long time finishing process, and one of the reasons I take more $ for a wooden brush.
I saw the Bush Oil at the Woodworkers show and spoke for a long time with Mr Bush about the application of his oil, this stuff is quite good.