Gearing up a warlock is much more difficult than gearing up a melee/ranged character. It sounds like the raid scene on your server is not as robust as Sarlona which is unfortunate because there is so much best-in-class gear in Defiler of the Just for a warlock.
I use epic chord of reprisals for my charisma +11 item. That and Libram are the only non-raid +11 or better items in the game. It is possible to get a +11 charisma item in random loot, but it's very rare and doesn't come with augment slots.
Here is the gear setup I have on my alt without the past lifes and raid gear:
https://www.ddo.com/forums/showthrea...=1#post5712331
Unfortunately Ultimatum will result in a 50% arcane spell failure rate so it's probably a non-starter. The major drawback with skyvault shield is that it only has a +7 enhancement bonus so it pushed you into a weapon with a high enhancement bonus in your main hand to maximize the implement spellpower bonus.
http://ddowiki.com/page/Arcane_spell_failure
Until you get the dissolution you can request someone to help you craft the mobile ring of acid lore which will be 14% if you don't craft it yourself. This also gives you +2 dodge and +2 dodge cap which is one of the few gems left with cannith crafting. You can slot Acid 138 in your shield. While this doesn't match dissolution, I still thin you are better off with Epic Rod for mythic for implement bonus+ meridian fragment and a slightly lower lore than you get from random loot.
All you have to do is advertise on your server marketplace forum for help crafting and someone will help you out if you provide the mats.
The ring is something I recently switched and just now updated my post. If you don't have the mysterious cloak you can substitute jeweled cloak (best you can get) or even ghost-waking cloak for 15 damage reduction. You can also slot a prismatic cloak with a useful ability. When the mysterious cloaks come back to the vendor just get the best you can get if you don't have enough remnants saved up for the level 21 version.
If you use the rod of mythant I would try and slot a meridian fragment. This ia raid item, but you can get them on the ASAH and sometimes even plat AH on Sarlona. There is one going for 1.8MM on the plat AH or several starting at 14 shards on the ASAH.