@Sickle-cell Well yes, sort of.
Unintentionally, he may have created a weapon which, if somebody had
incredibly precise control of blood, could be used to great affect, but it isn't self replicating, it is finite, and although
someone who controlled blood could probably make it survive longer out of a human body then it's creator ever intended, it would still degenerate after not very long since like I said, it requires a narrow temperature range (the internal temperature of humans) to remain stable.
So ya, Sickle-cell could use it, by accident or intentionally, but even then as the blood cooled from being whisked through the air, touching surfaces colder then internal body temperature of humans, etc. it would start falling apart (on a molecular level just to be clear) faster as it gets cooler. Unfotunately, like I said, Ifrit designed it to be delivered in an
excessive dose, so there would probably be, to begin with, enough to kill, if it could be introduced intravenously (so into their blood, while it is in their body) 50 people. This is actually a really tiny amount of liquid, even given that the majority of the solution would be a buffer fluid to keep the actual toxin stable without being in any of the aforementioned requisite states (temperature, pH, human body).
Also, I should have put a greater emphasis on this in the explanation, but the explanation was already sooooo long, the unique "Omega-protein" that Ifrit uses actually destabilizes and denatures normal carbon based proteins (once again, conveniently this is a real thing) meaning it would also, actually start making the blood, not blood. Blood, after all, is just a solution with a bunch of hemoglobin, a protein.
This chemical would in other words come at a cost for sickle to use, as yes it would be super-deadly, but it would
also be constantly destroying the blood it is in. It wouldn't be rapid, it would be pretty slow actually, I am just saying that it wouldn't come without costs.
My point being, it is certainly powerful enough to make the plot more interesting, but it isn't enough to skew the direction of a
war, just a battle.
Edit: Also, there is more foreshadowing going on here but I don't want to totally spoil it, but to be fair I may call on the jury to recall this explanation in the future. Don't worry it isn't anything OP, just useful to the plot later on.
Also, I just remembered to clarify again, it must be intravenous to be effective. If it goes in through their mouth, the botulinum toxin mechanism will not be effective, although the "Omega-protein" actually still will, and it would be the equivalent of drinking low molarity acid. Humans actually eat the botulinum toxin in lethal dosages all the time, it is common certain foods like honey, but our digestive systems are effective at filtering it out.