Finally a response!
Okay so Garfiel has his instinctive reaction, analytical prediction and ESP which can sense dangers even when he isn't directly looking at his opponent
The water amp is not significant enough to make him greater than Garfiel in AP and Garfiel is also extremely tanky, he also has great healing and can even regenerate fatal blows if he transforms
Garfiel could also manipulate the ground to attack him from multiple angles just like Percy does so they are pretty even on that too
Overall they are pretty similar with the only major advantage being skill in Garfs favor
I don't think I'd fully agree that skill is definitely in Garfiel's favor. Percy is a naturally talented swordsman. His skills continue to grow as time passes, capable of holding his own against and defeating larger, more experienced, and more powerful opponents, including several monsters and Ares, although he
had underestimated Percy. In The Lightning Thief, he was able to disarm Luke, the most skilled swordsman at Camp Half-Blood for the last three hundred years, in a swordsmanship class with a complex maneuver he just learned with a water amp-literally his first time training with a sword. In The Sea of Monsters, even when Percy had only trained for a year at the time, he was already regarded by other campers to be better than any other camper in Camp Half-Blood at swordplay in the last 100 years, with many comparing him to Luke. At this point, Percy sparred against entire cabins at a time, and rather easily beat the guys from the Apollo Cabin, and every demi-god has enhanced senses and reflexes. Despite being out of practice when he fought Luke, Percy was briefly able to fight him off, but was overpowered rather easily due to being rusty. In The Battle of the Labyrinth, Percy was skilled enough to defeat Ethan Nakamura and beat a recently awakened Kronos without the Curse of Achilles. In The Son of Neptune, even after losing the Curse of Achilles, he fended off an entire army of continually resurrecting ghosts by himself while still protecting Frank and the golden eagle of the legion, as well as easily defeated an Amazon. According to Frank, Percy "fought like a demon." When possessed by eidolons, Percy fought Jason on even footing (Piper couldn't believe the speed of their sword fighting which she described as a 'blur', as they exchanged multiple blows that lasted only a second). It should be noted that Jason was distracted by Piper's charmspeak twice, which allowed the possessed Percy to eventually exploit the opening in Jason's defense. In The Son of Sobek, Carter admitted that Percy was a way better swordsman than he was even with Carter's specialty being combat magic and swordsmanship. The only people shown to be his superior are Luke (who was possessed by Kronos at the time) and his half-brother Chrysaor, who is pretty much only known for being the son of Medusa and his swordsmanship-hell I'm pretty sure his name translates to golden blade. In Son of Neptune he goes so far as to thoroughly trounce Polybotes, the giant tailor-made to kill his father, single-handedly, only needing Terminus' help to finish the job, because giants can only be killed by a god and demigod working together.
I'm also not sure how celestial bronze would interact with Gargiel. However, it was able to harm the Egyptian magicians, and I don't believe he's lycanthropic at all, so I think it would still work. Which is important.
Because celestial bronze and imperial gold attack your very essence. This is later backed up when Jason is stabbed by an imperial gold sword. Just getting cut by celestial bronze is debilitatingly painful, for both demigods and Egyptian magicians. I'm not fully familiar with Garfiel's backstory, but they are of similar ages and Percy has fought in two wars against immortals and monsters, many of which were stronger, or faster, or even had many abilities to fight against, not to mention his experience with the Egyptian stuff as well. What I truly believe would be Garfiel's best advantage is his healing and recovery when transforming, though it's not anything Percy hasn't fought against before, and I don't think it's as powerful as having Gaia continually healing all wounds or being completely immortal unless specific conditions are met.
