Mercury, what can't it do? Used in skin treatments and mood tinctures in the Old World, it can also most readily be extracted from the swordfish that circle Aeternum. Used ubiquitously by healers across the globe, mercury can be administered in its liquid or solid salt form. The mercury content of the Aeternum swordfish seems irregularly high, but I cannot compare it to an Old World fish without returning home, which is impossible with the storms that haunt the coast.
For now I must rely on anecdotal evidence from the other alchemists who have seen Old World swordfish, as unreliable as those observations can be.
-Park