Reddit please help me find this book.

I have tried all the googling I can. I read this book when I was still in like..5th grade, so the memories are pretty vague. I remember it was about this kid(young adult?), and his travels I guess. He befriends this badass knight who doesn't appear too much in the book. I remember now after typing some, they think that he dies somewhere in the middle of the book, I think it was from a castle collapsing, but turns out he lives and comes back at the end of the book. The knights name began with a g. I remember his name being oddly spelled, like Gaeywin or some shit like that. I remember at the end of the book there's battle, and the big bad guy riding a horse in black armor fought "Gaeywin"(he made his unexpected appearance because people thought he died), and Gaeywin won? I remember the bad guy died and Gaeywin was injured really bad. I forget if he died or not. It was either he died, or they thought he was going to die and he barely lived. I know this is the least descriptive thing ever, but this is from 11 years ago. If this sparks potential for anything from anyone just name drop it, I'll google after that and see if it's it, any help would be super appreciated.

Edit- It is not Sir Gawain. I'm 90 percent sure about this. I think I could have pronounced that in fifth grade...I hope at least, lol.