Steve,
Don't worry about sanding anything before the glue up. Work the epoxy into the splintering as good as you can...use a piece of paper or unwaxed floss to pull it into the tight portion of the splinter.
Cover with wax paper and wrap tightly with electricians tape... at least 2 or three layers.
When the glue is cured, sand smooth with some 180 grit paper and finish with 220. Watch for sharp points or edges when you start sanding.
Apply finish... you could prepare some Massey finish. It's 4 or 5 parts acetone to one part mixed epoxy. Wipe on with a single pass. Let it cure, sand, wipe more until desired finish is achieved.