Firesweep Lance+ for Cordelia +ATK/ -HP?

Personally, I think a Brave Lance Set would be better for Cordelia with an ATK boon but instead of Death Blow, perhaps Life and Death + Desperation would produce much better results since regardless of the amount of merges she has, 1 Ardent Sacrifice would bump her into Desperation range easily!

I have a Cordelia with the same IVs as yours, and I have to say with Firesweep Lance she may deal less damage than a Death Blow and Brave Lance+ build, but she can secure kills easier and safer with a Firesweep Lance. Additionally, I use Darting Blow on her but any other skill that boosts her speed is fine as well.