I'm really not sure you understand what a disadvantage is.
Either way there will be a disadvantage.
I: You will have the full set advantages but would probably be using an awful weapon.
II: You use your standard weapon but don't get all of the advantages of the set.
If it's not broke don't fix it. Why should the weapon become part of the set? The items that affects dueling the most? Only two of the sets use products, why not add products to all of the sets if sets must be edited. IMO more sets would be better than making changes to the current ones and sets for higher level players so they actually get something that you have to work for.
So you think it should be 40 because that would be a "possibly a good level requirement"?
Oh how ridiculous.
Lets take the gentlemans set for example. If they added a weapon to it all it would do is add more LP's to the set. If you used the set without the weapon you would have the same LP's using the set as you would right now.
Lets say they added the golden colt to it for example. The golden colt would not suddenly do less damage just because it was added to a set and you used it without the set.
So there is no harm no foul here as far as dueling goes. You could still take that weapon and go duel with it with no change.
If they added a different wimp weapon to the set use the set without it. Your trade off would be if you did not use the weapon they chose you would have a few less LP's using the set than someone who did. But you would still have the same LP's as you would right now using the set.
But that would be your choice to do so, not someone else's.
I understand what a disadvantage is quite well.
But in this case there really is none.
1. Those that want the extra LP's could use the set with the weapon that was assigned to it.
2. Those that did not like the weapon could use a different weapon with it and still have the same LP's they do right now.
3. There would be no effect on dueling.
So there is under these condition nothing "not broken being fixed".
But there would be players
making their own choices about what to use/not use and being responsible for those decisions.