Legendary Seliph

Weapon: Arcane Eljudnir (+Def or +Atk)

Assist: Positional Assist / Preference

Special: Galeforce / Bonfire / Ignis

Passive A: Atk/Def Catch 4 / Sturdy Surge / Atk/Def Solo 4

Passive B: A/D Near Trace 3 / Flow Force / Lull Atk/Def

Passive C: Joint Drive Atk / Atk/Def Menace / Preference

Sacred Seal: Heavy Blade / Atk/Def Solo
 

• Legendary Seliph got a much needed buff in the form of the Arcane Eljudnir, finally giving him a great weapon that does not lock him into an underwhelming Enemy Phase unlike his exclusive weapon. Arcane Eljudnir boasts a plethora of powerful effects: Slaying, Guard, guaranteed follow-up attack, and follow-up prevention. 
• The weapon is a natural choice for a Galeforce set as it’s guaranteed follow-ups will bypass Legendary Seliph’s low Speed, and he will have very little trouble passing Heavy Blade checks thanks to his massive Attack. 
• A/D Near Trace is Seliph’s best B slot option as it gives him a significant amount of after combat mobility thanks to Canto. Flow Force is another good option that negates Seliph’s Attack debuffs during combat in addition to negating follow-up prevention effects that would force him into Speed checks. Lull Atk/Def is another option for foes that rely on buff stacking, which can be worthwhile instances.
• Seliph will want an A slot that raises his Attack and Defense: options like Atk/Def Catch and Atk/Def Solo 4 are excellent for this.

Weapon: Arcane Eljudnir (+Def) / Virtuous Tyrfing 

Assist: Positional Assist / Preference

Special: Noontime

Passive A: Atk/Def Unity / Sturdy Stance 3 / Close Def 4

Passive B: Holy War’s End

Passive C: Joint Drive Atk / Preference

Sacred Seal: Atk/Def Catch / Sturdy Stance

• Seliphs base kit leans him more towards an Enemy Phase role, but Enemy Phase cavalry tend to pale in comparison to their infantry counterparts due to their lack of skills for the job. Still, he can function decently as an Enemy Phase Melee Specialist, or as a Distant Counter unit on a budget.
• Arcane Eljudnir is a significant improvement over Virtuous Tyrfing, but it will be a somewhat rare weapon to acquire due to being locked to Rearmed Lif at the time of writing. If it’s unavailable, Seliph’s innate Virtuous Tyrfing can be used in its place.
• Holy War’s End gives Seliph an automatic follow-up attack that occurs before the foe can counterattack as long as he’s above 50% HP, greatly increasing his Enemy Phase KO potential.
• Sturdy Stance 3, Atk/Def Unity, and Close Def 4 are Seliph’s best options when it comes to A slot skills. All of them are good choices: Sturdy Stance 3 for Guard, Atk/Def Unity for protection from stat debuffs, and Close Def 4 for negating the foe’s buffs.
• Seliph’s seal is best used on an extra Attack and Defense boosting skill such as Atk/Def Catch and Sturdy Stance.