Is the picture at the beginning of the Darkness that comes before, the first page of the Compendium of the First Holy War?
The script that separates the different sections.
Perhaps relevant, there are 3 unique drawings, and they come from the original Rankine covers that were published with the first printings of TDTCB, TWP, and TTT. All the following books have the same picture as the one provided in TTT.
It may also be noteworthy that the drawings printed within the books differ ever so slightly from the published dust jackets.