I like taking mechanics and turning them into character traits.
Mechanic-wise, Leon's HP and defense are about on par with Philia's. He's a fragile speedster. But also a crit master. A glass cannon.
The remake even has a skit about Stahn being able to take a hit better than he can. A punch that Stahn reels a bit from would probably lay Leon out entirely.
I will accept without any argument that Leon is by far the most skilled party member, but I refuse to believe that he'd stand a chance against a good chunk of them in a battle of raw strength. Sit him down for arm wrestling and he's walking away with a dislocated shoulder.
But. His body apparently changes between PS1 and PS2.
That demo disc interview has Rutee remark on how ROCK HARD all of his muscles are. So he is an ultra ripped twig in the original.
Director’s Cut’s hotspring sidequest shows he’s the only male character without any visible muscle definition. All the other boys are muscular as hell, and Rutee who stands in a similar pose as him has very visible muscle to her arms. Philia’s sprite may look soft but she holds Clemente, the largest Swordian, directly above her head for extended periods of time without shaking. Chelsea actually has a little definition on hers and archers need plenty of upper body strength. So yes in DC continuity Leon probably has the least muscle or upper body strength of the entire party.
<insert virgin remake vs. chad original memes>
Oops that was accidental wording but hey we're also pretty sure DC Leon is a virgin too anyway based on that one sidequest where he aborts some dirty snark like 2 words into the sentence because he's just that embarrassed
It's nothing but headcanon but I feel like the whole motion sickness thing lends well to theorizing that his immune system might be fragile, too.