Well, I would like to throw another idea out there that kind of getting rid of the claimed things.
A big difference between this game and a lot of other games is that people want to just start at the End Game with max stats and the best items. Now, that would be fine if you're playing a game like Dark Souls or Metal Gear or something else because everyone has the opportunity to get everything. In that way, the multiplayer aspect of those games are very inclusive. Here, not everyone has the opportunity to get everything, because the more established people have already scooped up the items. That makes this game very exclusive and rather hostile. A work-around for this is that people can just make custom items that do just about the same things as these exclusive items, sometimes more, but some people don't like that either.
Why not just do away with the claimed list and use it as more of a choice list. People can choose to get the samehada if they want, or they can choose to get the Kiba blades, or they can do something else. That's because it's pretty hard to keep track of every little piece of activity that goes on and it will be more like a chore for the people who choose to have 'claimed' items because they always have to check in with somebody. Kind of like being on parole. The reason why this could be viable is because it allows people to build their characters however they want and the odds of two people using the same item interacting with each other are fairly low (because some people prefer to stay with their cliques and comfort zones).
And actually using the items frequently can be a bit hard to do. Like myself, I have plenty of items in my collection (which I need to get back to updating again lol I hope I pick up this advancement cycle) which are mostly either used by my NPCs or just collecting dust. I make the items just to dump my imagination onto 'paper' and develop lore for my character and his lab and the world around him. If I get The Legendary Shovel and have it claimed, the need to dig a trench might not be something that happens frequently.
It's just an idea. Because the exclusivity of the weapons in this game sure do seem to be causing as much trouble as the bijuu did not too long ago, and it would be nice to finally come to a conclusion. And if a weapon could be made once, why can't it be made again? Though, not a lot of people want to RP as a smith or inventor because it's a different play style
It's too bad, because I think having variety in characters like that would be neat.