Cherche's personal weapon plays directly into her previous best set utilizing  Brave Axe+. Given Cherche's extremely high attack she can initiate and kill most enemies in the game. Both her new personal weapon and the introduction of Death Blow 4 allows Cherche to gain even more power while also allowing her to score extremely well in Arena.
Boon/Bane Cherche's best boon and bane set is +Atk and -Spd to maximize her personal weapon's power while dumping her worst and least consequential stat.
Weapon Her personal weapon Cherche's Axe is simply a Brave Axe+ with 3 more MT. Her Special refine gives Panic Ploy 3, which is an overall excellent skill that was generally worth the C slot, but now is just free. Along with Cherche's pretty good HP she is able to panic everyone except the other highest HP melee infantry and armor units. If you have no need to Panic Ploy, then +Atk works, just to squeeze out a little more damage.
Assist Like other fliers, Cherche does best with Reposition, though whatever assist you want (such as a dual rally for score) also works well.
Special
A two charge special like Moonbow allows Cherche to activate it during each combat when combined with the Heavy Blade 3 seal. This allows Cherche to win some matchups she otherwise may not be able to.
Alternately, Galeforce allows for Cherche to freely move again after her second combat, allowing for greater movement capabilities. This scores well and because she already hits so hard, only affects some ultra defense neutral matchups or triangle disadvantage matchups.
A Skill
Given Cherche's insane player phase potential, Death Blow 4 becomes the obvious choice both to maximize her damage in addition to maximizing her score.
B Skill
If one wants to squeeze out wins against the tankiest units and maximize her SP, Chill Def 3 is perfect for her, severely hampering the tankiest unit on the enemy team. Without Weapon Triangle Advantage Chill Def gives Cherche +14 damage.
Alternately, Hit and Run provides Cherche with a mechanism to escape combat after initiating.
C Skill Guidance 3 gives Cherche good support capabilities for a mixed emblem tea, allowing for better movement options. Alternately, other skils such as Flier Guidance 3 or other buffs work well.
Sacred Seal
Heavy Blade 3 allows Cherche to almost always get an extra charge during each attack, due to her extremely high attack. This lets her very quickly fire off special abilities.
Alternately, if you want more support skills such as Guidance 3 are good seal slots. | 
Optimal
Very high investment
High investment
Alternative
Assault
Creative
