Sands of Menechtarun epic items

The summer before level cap went to 28 they increased drop rates several places including sands seal/shard quests - this was announced officially. Then when thunderholme was released it appeared to revert back to the old drop rates. This was never announced officially and forum discussion was completely ignored by the devs.

Zawabi's Revenge Raid Items

 * Shards for all of these items drop only in the epic raid, Zawabi's Revenge. It's quite common to get one.
 * Seals drop with a low drop rate in the side chests of epic Against the Demon Queen and also drop in all chests in Wiz-King, Offering of Blood and Chains of Flame at a extremely low drop rate.
 * Scrolls for these items drop from any dead monster in epic Demon Sands quests (except the raid).
 * The base raidloot may also drop on epic difficulty, at a lower rate then on elite difficulty due to the vastness of the loot table.
 * The 20th rewards list varies whether the 20th completion was done on heroic or epic difficulty. If done on heroic, the list will include named items that drop inside the raid. If done on epic, the list will include a choice of 10 random epic shards of the 16 named items that drop in this raid. {You cannot obtain shards for the any of the other named items found in the wilderness, wiz king, offering, or chains of flame via this 20th list}. This epic 20th rewards list is special to Zawabi's Revenge and does not apply anywhere else.

Sands of Menechtarun Explorer Area Items

 * Shards for all of these items drop in the epic raid, Zawabi's Revenge and also in the Epic Chest of Epic Against the Demon Queen. It's extremely rare to get one in the raid, and uncommon to get one in ADQ1 - and rarer still to get the one you want. They are the rarest shards in the game.
 * Seals drop with a low drop rate in the side chests of epic Against the Demon Queen and they also drop in all chests in Wiz-King, Offering of Blood and Chains of Flame at an extremely low drop rate.
 * Scrolls for these items drop from any dead monster in epic Demon Sands quests (except the raid).
 * There is no epic version of the sands themselves, so you will need to acquire the base item from the regular sands or in trade.
 * The best calculation known about the odds of pulling a Seal of the Ring of Spell Storing is: In ADQ I you have 1 in 1666 chance for getting that shard. In ADQ II, you have 1 in 4666, aka lower.
 * The best calculation known about the odds of pulling a Shard of the Ring of Spell Storing is: In ADQ I end chest you have 1 in 6700
 * The extremely low chances are partly due to the very low drop rates and the fact that there are 32 wilderness named items. The estimated of the best chance of obtaining a wilderness seal from the three Against the Demon Queen side chest seems to be 2%
 * Using astral shards to reroll these side chests would take on average 20,000 astral shards before pulling a Ring of Spell Storing Seal (still need Shard from end chest).
 * Creating a specific Epic Wilderness item is the most difficult Magic Item in the game to obtain. Expect to farm many years for such an item.

An Offering of Blood Items

 * Shards for all of these items drop in the epic raid, Zawabi's Revenge and also in the Epic Chest of Offering of Blood. It's very rare to get one in the raid, and uncommon to get one in OOB - but at least there's only four of them, so it's not too hard to get the one you want.
 * Seals drop with a low drop rate in any chest in Offering of Blood.
 * Scrolls for these items drop from any dead monster in epic Demon Sands quests (except the raid).
 * The base items drop on epic difficulty at about the same rate as they do on non-epic.

Chains of Flame Items

 * Shards for all of these items drop in the epic raid, Zawabi's Revenge and also in the Epic Chest of Chains of Flame. It's very rare to get one in the raid, and uncommon to get one in Chains.
 * Seals drop with a low drop rate in any chest in Chains of Flame. The matching specific items chest does not have any higher drop rate then any other chest for each seal.
 * Scrolls for these items drop from any dead monster in epic Demon Sands quests (except the raid).
 * The base items can be found in the quest only on non-epic. They do not drop on epic difficulty.

Chamber of Raiyum (Tomb of the Wizard-King) Items

 * Shards for all of these items drop in the epic raid, Zawabi's Revenge and also in the Epic Chest of Chamber of Raiyum. Note that acquiring the Epic Chest requires you to slay Raiyum, Hafez and Hami. Shards are very rare in the raid, and uncommon in Wiz-King.
 * Seals drop with a low drop rate in any non-Epic chest in Epic Chamber of Raiyum.
 * Scrolls for these items drop from any dead monster in epic Demon Sands quests (except the raid).

Drop rate discussion: https://www.ddo.com/forums/showthread.php/496533-Desert-Loot-(Seals-and-Shards)