How to salvage Oblivion Walker Achievement after messing up Pieces of the Past

I want to do the Oblivion Walker achievement but made the mistake (some days ago) of letting Silus live in the quest "Pieces of the Past". I did not get the quest item that way, which is required for the achievement.

How can I salvage this situation? Do I have to load the old save game, losing several days of playtime, or is there a better way?

Solution 1:

According to the Elder Scrolls wiki, if you miss an artifact the Oblivion Walker achievement can still be obtained by getting both The Ring of Hirscine and the Savior’s Hide from the Ill Met By Moonlight quest.

UESP has instructions for doing this:

It is entirely possible to obtain both the Ring of Hircine as well as the Savior's Hide. In order to do so, first you must help Sinding eliminate the remaining hunters. After doing so, speak with Sinding to complete his quest objective, then kill him. When you remove his skin, immediately avoid contact with the Hircine's spectral avatar (or back out of the conversation) and exit the cave, leading you to the spirit of the white stag, which will then reward you with the uncursed Ring of Hircine. Now re-enter the cave and speak with Hircine's spectral avatar to receive the Savior's Hide.