|Roy's new weapon refine redefines Roy as a defensive sword user with mixed defenses.
Roy's preferred boon is +Spd, as with 31 base speed he can increase his speed to a point where he can stop getting doubled, which will severely increase his bulkiness. Roy's preferred bane is -HP, being the generally most useless stat and otherwise letting him run ploys.
Binding Blade is the weapon that makes this build work, as not only does it increase the base effect of the weapon, but it also adds dragon effectiveness in addition to giving him effectively Quick Riposte at level 5 (50% threshold).
Reposition is a strong assist skill for any tanky unit, and Roy is no exception.
Moonbow is generally the best assist for him, as its low cooldown lets it proc every fight and, unlike Glimmer, allows him to cut through bulkier targets.
If one plans on getting doubled, then a 3 cooldown skill such as Luna or Bonfire are also viable.
Distant Counter allows Roy utilize his good resistance to help fight mages. Being able to ounter units at any range broadens the amount of units Roy can deal with.
Alternately, if you only want Roy to be a melee duelist then Steady Breath is also strong, letting him fire off Moonbow every counter attack, but losing a wide berth of other units.
With Quick Riposte built into Binding Blade, Roy can afford to run different skills for his B slot. One can go two ways: defensive or offensive.
Guard 3 is the defensive route, allowing Roy to neutralize threatening skills such as Bold Fighter, shutting down enemy's specials which will likely get him killed.
Wrath 3 is the offensive option, allowing Roy to empower his special attacks, especially if running the Steady Breath build.
Roy's C skill is very open, and team dependent. Any Hone/Spur/Drive is already fairly decent. With 28 natural resistance he has enough to use ploys on many melee units, making Atk Ploy 3 or Def Ploy 3 fairly good on him. Alternately smokes can be effective for letting Roy tank additional enemies after the first one.
Close Def 3 is overall the best seal for Roy, as his naturally low defense leaves him vulnerable to melee attacks.