head to head
Neither is meaningfully harder - they pose close to the same test. The widest gap is reads, and it is a single point.

Execution · Practiced Mastery
The black-sheep sequel whose passive enemies and dominant guns sand the series' skill ceiling way down.

Execution · Practiced Mastery
A musou-style hack-and-slash letting players mow down hordes as One Piece characters.
Devil May Cry 2 leans Execution (Practiced Mastery); One Piece: Pirate Warriors 4 leans Execution (Practiced Mastery).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Devil May Cry 2
Infamously easy; guns trivialize most encounters
One Piece: Pirate Warriors 4
crowd-clearing combo execution against hordes
One Piece: Pirate Warriors 4 leans a little harder on reads, though the gap is small.
Devil May Cry 2
Passive enemy AI never pressures, let alone adapts
One Piece: Pirate Warriors 4
enemies are scripted mobs, not adaptive
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Devil May Cry 2
Flat authored levels hide little
One Piece: Pirate Warriors 4
minimal randomness in stage encounters
Devil May Cry 2 leans a little harder on optimization, though the gap is small.
Devil May Cry 2
Amulet builds and boss patterns fall fast
One Piece: Pirate Warriors 4
character builds and combo routing are learnable
A matching score does not mean a matching test. Two games can both sit at 10 on execution and demand completely different things of you - which is why the reasoning above matters more than the number beside it.