That aside, here's what would happen with each option.
Option A:
1. Beginners would be left unable to pick up Hockey Masks (
http://helmet-heroes.wikia.com/wiki/Hockey_Mask ) and Log-Splitting Axes (
http://helmet-heroes.wikia.com/wiki/Log_Splitting_Axe ). Mind you, even the earliest players can kill Purple Goos, and some beginners would be killing Green Walkers by Level 10.
2. Players who like to prepare for new equips would be held up big time. For example, if I'm in Level 320 and I were to get all the stuff required to get a Mystical Tribal Mask, which requires me to be in Level 375 to equip, how can I buy the mask and thus get rid of all the junk I'm carrying around?
3. Beggars would make legit players carry junk for them,
4. Accessories have low level requirements (Evil Wings can be equipped at Level 80 and Jetpacks can be equipped at Level 25), which means they can still be carried and potentially duped. Mind you, accessories are sellable, tradeable, and droppable.
5. Underleveled legit players (as in NOT dupers) may be unable to pick up any event craftables, such as the Divine set and Mystical Tribal Bow from the Valentine's Day Yellow Hairy Monster event.
6. Game would glitch if overleveled items exist in current players' inventories.
Option B:
1. Better implemented with a duped-item checker. Let's say Marvin the Martian is Level 300 and he has two Atomic Helmets on him: one legit, and one duped. Marvin can trade/sell/drop the legit helmet, but NOT the duped helmet.)
2. Accessories have low level requirements, so they would still be tradeable/sellable/droppable. I recommend the level requirements for accessories to be increased to 200 or 250 for this.
3. Underleveled legit players cannot sell off event craftables. In other words, if you're in Level 300 and your inventory is full of Mystical Tribal Bows you picked up from the Valentine's Day event, that would mean you're stuck with million-dollar garbage cluttering your inventory, meaning you can't pick up any item drops until you get to Level 375.
My way of going about it is more simplistic.
Option C:
Duped-Item Checker in Inventory (No Level Requirement):Player: Marvin the Martian
Level: 300
Item 1: Atomic Helmet (Legit)
Source: NPC
Results: Drop button exists. Sell button exists. Offer button exists.
Item 2: Atomic Helmet (Legit)
Source: Obtained from ihasarchery (originally from NPC)
Results: Drop button exists. Sell button exists. Offer button exists.
Item 3: Atomic Helmet (Duped)
Source: Marvin the Martian
Results: Drop button removed. Sell button removed. Offer button removed. You're stuck with your duped item, Marvin!
Item 4: Atomic Helmet (Duped)
Source: Obtained from Chewbacca (originally Duped)
Results: Drop button removed. Sell button removed. Offer button removed. You're stuck with your duped item, Marvin!