I was thinking for each skill, or most of them, once you reach a high enough level, a certain quest is availiable that only a person with an expertise of some kind can complete.
Example reach level 100 marksman, you and some other archers have to clear a certain mountain of its dangerous dragon population, careful though they like aerial combat.

I agree, but I voted no for fun.

What would you get by doing them? An item related to the skill? Money? A perk?

Dunno, an ultimate weapon, a bow with 12 strings and can shoot 390 arrows at a time?

I don’t mind what I get but I think they should make these quests a bit more interesting. I mean sure, you need to prove your skills in the area by doing a quest related to the skill. But the quests based on this in oblivion were a little bit boring. I would like to see more development into these quests.

Already kind of sounds like there trying to go for something like that but i don't think its 'master skill' related. And some, least in examples seem kind of like mini-events. Like villages knowing your good at illusionary magic so they want to see some pretty lights from the master mage guy.

The idea of a 'master quest' for individual skills I think would be a bit silly but I think basing it around some overall archetypes it would be pretty nice. For instance if you've maxed out 1h or 2h considering your character a Master of Melee combat for that, or Archery as mentioned would work. Also splitting Magic up in that way with destruction vs more neutral stuff. Also certain Stealth things could be interesting.

Ultimately its all flavor stuff, and that can really make a game feel more immersion inducing so im all for it if it works out well.

Maybe, as an alternative, you need to do a quest to master the skill, leading toward a great reward!

Just my two septims (bad pun)