This suggestion is originating from dual fame (df) issue I'm facing.
Right now, dual fame is obtainable through :
1) war and scenario (max up to 15 df per event)
2) daily quest for turning in random nation secret for 10 df daily
3) repeable quest for turning in Dark Signets for 1 df per Dark Signet
For #1 on war/scenario, being a player with work and life commitments and living in a different time zone which make the timing for those events to be sometimes very unsuitable to participate in, getting dual fame can be really frustrating. Players have no control/flexibility over obtaining the dual fame.
For #2 daily secret turn in, this is okay I guess, since players have control/flexibility to farm the secret daily. No issue with this, although higher chance to drop the secret would be really great! (Just saying, not suggesting/requesting)
Now on #3, the drop rate for Dark Signet is pretty low, which is fine.
Problem is with the way to obtain it is only through killing mobs of 100+ levels. Normally this is done efficiently in group, killing mobs in Venom Dungeon. Most of the time, it's the tank who gets the loot i.e. Dark Signet.
Of course we can ask politely to share the loot, but in reality, it's not going to be easy given how rare it drops.
People will tend to be reluctant in sharing.
At the moment, there is no other use for red/blue signets. It's not getting picked up (rarely) due to them being next to useless other than to create a guild, or something else which I may not know of.
So why not implement a feature where you can turn in red/blue signets to Dark signets.
Or for easier solution, to add another NPC repeatable quest who accepts red/blue signets in exchange for dual fame points. This way, players have more options and more importantly, control in getting dual fames.
Of course the amount required per dual fame can be set and adjusted e.g. 50 - 100 red/blue signet (or even more) for 1 dual fame.
This at least gives players purpose to loot the red/blue signets at low and high levels.
I would request to add dual fame envelop in mall with limit purchase/use of once daily, but I feel that it will be a bit too much to ask for.