Let me get it short : OP wants a way to prevent every better geared player to be able to need the loots that suits their class, just for him to increase is chance of getting it for a class he does not play?
How does it work? The game check every ilvls for every class of each pelayer in the duty, then if they are above thoses of the OP, they cannot need the item?
Seriously this is one of the most self entitled topic I'v seen in a while. Who do you think you are?

The whole game revolves around new players, throwing loots at them like candies for litteraly NOTHING. But no that's not enough, let takes off the privilege of veteran players to "need" on their class specific loots, right ?
We are already poorly treated as veteran players, when it comes to rewards (have you ever seen how is the loot system in raids? no, I'm sure you have not the slighest clue about how we can struggle to get one loot. If you are unlucky you will need 4 weeks raiding for an accessory, when the game litteraly now give you the same item for DOING NOTHING)
But naaaaah that's not enough! These filthy ellitist high geared players should not have the right to need items suited for their class.

Stop trying to change a whole system perfectly fair just because YOU don't want to play the game how it is intended to.

And furthermore, I've yet to see someone refusing passing on a item if ask nicely. So the only thing I see here is a SPOILED LITTLE BRAT, who refuse to communicate and yet expects all other players to be punished for simply playing the game before him.
All this maths ans stats won't hide the fact that OP just sounds like a selfish person that just want everything handled down to him just because he don't want to communicate and can't accept the fact that he is not entitled to anything.
That kind of attitude should be awarded with a nice reality slap between the eyes.
You are not the victim here. The whole system is fine and fair. You want that class specific item? You play as that class or you ask politely. All your bragging won't change anything and furthermore, I will gladely roll need on everything I can if I happen to run a duty with you, OP. And I hope many players which tried to point your nonsense will do the same.