Lore Jockey players

(Playing Dnd 3.5) I’ve been having problems with a player where he’ll trying to get me to homebrew rules for him based on these lore points. Recently he wanted to get his blade serrated to do bleed damage. After researching I found that wounding does bleed damage per round based on the amount of successful hits they’ve got on the creature. I brought this to the player and we calculated the cost. ( I think it was somewhere around 18k gp, if I did it right becuase it’s a dagger and the wounding adds a +2 to its cost ) But then he brings up like a line, "can’t the back smith just serrate it himself", I pull a line, maybe they can’t do that just yet technologically do with out breaking the weapon. Then he gave me a line like, "but the dwarves have the goblin ripper that was super small serrations". How would I handle a player that that I have to abide by lore that he’s read in from the dnd lore books? ( this may be my fault as I set the campaign in the sword coast so I don’t have to make a new world for them to run around in)