Neomuni made SIVA safe. Quicksilver and cloudstriders show it's possible. Doesn't have to be darkness-related. Just has to be "not Light". I personally think a "tech" (SIVA + Warmind/Valkyrie) subclass would have been awesome.

Yes quicksilver works but, it’s no longer SIVA at this point it has thousands of years worth of refining to get it to that point it’s no more SIVA than a Chihuahua is a wolf, or a orange is a citron. Not to mention that the price of wielding quicksilver as a cloudstrider is the moment the operation is you only have at most an additional 10yrs left to live (if something else doesn’t kill you first). Judging from the fact that quicksilver was not created with guardians, specifically ghosts in mind it’s hard to say how a cloudstrider-guardian would survive considering SIVA was able to erode, damage and destroy many of the Iron lords ghosts it’s quite possible that a ghost may not be able to maintain and manipulate quicksilver or SIVA without it inevitably consuming the wielder (guardian and ghost). Ultimately if you want the classic rise of iron SIVA esk effects not the refined and controlled quicksilver version enough SIVA could easily be produced that it replicates out of hand and control of its wielder; the vanguard would never even allow that risk, in terms of permission or placing a bounty on the wielder. In summary I don’t think that SIVA could work but Quicksilver or valkyrie have potential but still probably with high risk in terms of lore; but nonetheless could be quite cool to wield.