I wish I knew you're not supposed to sell your old weapons.

[Daddy Kaneki]

I just learned that there's only one way you can get the Stiletto weapon, and you can only get it once; through a chest. I'm in Luin now, and I have all the materials for Kratos's current best sword except for the ♥♥♥♥♥♥♥ stiletto.

THIS is why old weapons are no longer part of ingredients for new weapons in more recent RPG games. Because this ♥♥♥♥ is unavoiable and frustrating unless you NEVER sell your stuff.

[Baffan]

Don't worry, you constantly get new weapons and it's not a big deal if only 1 character doesn't have the best weapon. Besides, it's better and easier to focus on all items during New Game +. Really, don't worry it's not punishing that much ^^

[Snood Dogg]

If you're talking about the Hydra Dagger, you can go back to Asgard and just buy one, I think. Unless Asgard is after Luin. It's been a while since I've played. But they have built the game so that if you miss an ingredient you're usually okay. You just might have to wait. You do get another Stiletto later in the game as well. For now, try to boost his armour, maybe change his title and make sure he's got good skills to use and you should be fine. I never really had any problems with Kratos in my various playthroughs, and I don't think I ever got screwed over just based on equipment, either.

[PlaceHolder]

For the effectiveness on getting new equipment, I'd say immediately getting the next set isn't that important.
An additional 50 damage isn't going to make your game THAT much easier.

For getting 100% completion, you can only get that on your 5th playthrough and beyond.
Although, you could get all the achievements on the 4th if you reload several hours of gameplay.

[JoeBob Riggs]

The game tells you not to sell your old weapons and armor. It says it in the first actual town you get to.

[Oddness]

Well ♥♥♥♥ new weapons, go Wooden Sword all the way(or at least to a specific fight to get a title for Lloyd).