I was going to suggest the ability to use any weapon reskin but it seems it was already done. I have thought of the problem you have with reskins like the shooting star, so I decided to post my solution to it.
Solution
You can only use reskins of your equipped weapons.
How it Could Work
You type in /reskin, you get a menu with the options primary, secondary and melee. You select an option and if the weapon you have equipped in the corresponding loadout slot has a reskin(s), there will be options to enable a reskin. If the weapon has no reskins then nothing shows up and the only option is to go back.
Example
I am playing as a pyro and my weapons are the phlogistinator, the panic attack and the homewrecker. I select primary and the only option is to go back, as the plogistinator has no reskins. I go back, select secondary and the same thing happens. I go back, select melee and there is an option to enable the maul reskin as that is the homewrecker's only reskin.