I would give Fortify to Frederick and keep Hone on Xander.
Because Your Frederick uses a Brave Axe so a +6 atk for him is really useful so Xander can give him this bonus and then Frederick would take Fortify by default.
I don't know if my reasoning is good but that's what I would do x)
I agree with the post above me, that Xander gets Hone and Fred gets Fortify. If you have the resources you can also give another hone to Reinhardt, so that everyone in the team gets the hone buff if they are in a square formation..it's not a necessary thing, but it's more useful than having 2x goad.