Refine change for my Chrom?

That might not be great.
Putting dew waste aside, your Chrom is likely going to heal the damage dealt to him.

That aside, the first combat is just as important for him. He want to be fully ready to bait in the enemy. With sealed falchion you're missing out in that first fight.
And this Chrom won't have the renewal heal, that he can use with reciprocal aid.

Sealed Falchion is best used with a fury and heavy blade combo, that way you can balance the aether heals with the fury damage. Staying just below 100% most of the time. But that would mean giving up steady breath. Which might not be the best choice.