David, for now, the only thing that might go wrong is the progression from the fourth to the fifth level.
Starting from the advancement from the third to the fourth Energy Level, if one were to fail or die, it could potentially cause damage to the soul. Accumulated damage would reduce the chances of successful advancement in the future. As for the consequences of failing to advance from the fourth to the fifth level, as of now, the least severe would be soul damage, with the worst being possible immediate death.
It is only after a full rotation of the cap raise for all nine Paths that the consequences for failing to advance from the fourth to the fifth and the fifth to the sixth levels will be reduced.
If Mr. "Knight" remains so naïve, he might also end up being unable to advance further due to too many accumulated failures.
Even if Aleister could take him once, twice... she cannot do it every single time.