Something to seal a neck I just sanded down?

[David Schwab]

id go danish oil. gives a bit harder protection than tung (from what ive heard) and feels very nice and smooth on the neck i finished with it. also you dont need as many coats.

I agree. I use Watco Danish oil. It's an oil finish with varnish added.

I've done entire instruments in it, and my main bass has its neck finished with it.