His lore states that the strength of his Noble Phantasm depends on the strength of the ally he sacrifices, where "Without anyone noticing, an extremely compact super-accelerator for magical circuits ……

Was used to momentarily super-strengthen allies, with super-offensive power while causing them to reach the super-critical threshold, which forms Chen Gong’s inhuman Noble Phantasm.

Allowing the strongest from our army to clash with the enemy’s strongest. "

Imagine if the damage of Chen Gong's Noble Phantasm used the ATK value of the sacrificed servant rather than Chen Gong's. Imagine the Damage youd cause by sacrificing someone like Jalter