It is possible to load every loadout you ever saved on any arsenal. If you use the customized arsenal to restrict weapons and vests etc. you are still able to load them
This is especially bad in TvT situation with teamswitching or certain special weapons that shouldnt be available at the Arsenal. But if you pick them up, go to the arsenal and save your loadout you are able to reload this loadout every time even if that weapon isnt part of that arsenal. Kinda even worse with vests in TvT as it makes you able to go "stealth" on the enemy team if you are able to wear their vest which shouldnt be available to you.
This kinda brakes the use of customized arsenals.