Add a way to claim special guild avatars after a player deposit a certain amount of guild coins. This system can incentive players to help the guild to grow.
For example every time you add guild coins to a guild deposit/inventory you get a currency similar to ED, AP and EP on your inventory. It can be increased only by depositing guild coins and it is account-shared or account shareable through the bank.
When you hit certain numbers, you can buy/unlock exclusive guild avatars or in alternative old avatars. These avatars can be either permanent or temporary. I'd like to see both types. Maybe some avatars can rotate as well. I think that this feature can persuade players to farm and give away their guild coins...
Here there is an example of the exchange/purchase with the new currency get by depositing guild coins (for this example, let's say that the trade from guild coins to the currency is 1:1):
-500 of new currency = hair;
-300 of new currency = top or bottom;
-150 of new currency = shoes or gloves;
-550 of new currency = weapon or accessories;
-500 of new currency = one full temporary set (30 days).
Hybrid purchase/exchange can be added:
-1000 of new currency + 50m ED = one full permanent avatar set;
-250 of new currency + 50m ED = one full temporary avatar set.
These are only a few examples, the numbers can change and maybe different rewards can be added too... This system can me modified in a form of "reputation" system in alternative to the currency. If you prefer to "build a reputation", then you will unlock the option to buy avatars after depositing a certain amount of guild coins, but you are still going to pay with a different currency like ED, EP or AP.