At this moment i think the safest way to use these -asset spells (alongside Eye of Chaos and Shroud of Shadows) is with Luke Robinson. The most effective usage of these spells comes with drawing one or even more -tokens. This comes with the advantage of getting bonuses even when missing the skill check, but also with the disadvantage to have to deal with an additional modifier of -2 (-4, -6, and so on). Therefore you want to draw -tokens but also need a way to compensate their drawback. So why Luke Robinson?
First of all every mystic can make use of Favor of the Moon to guarantee the draw of at least one -token. To compensate the penalty you can name this token with Recall the Future. Or as Luke Robinson you can pray to your Blasphemous Convenant to turn this one in an actual bonus to your willpower (combined with Recall the Future to +3 bonus). As an additional bonus the token goes back in the bag.
But how to generate these -tokens? Sadly mystics do not have a lot of ways to generate them. Promise of Power is a great skill card and highly recommended with this cursed style of play, but fortunately Luke can use Deep Knowledge to draw the needed combo pieces and fill up the bag. Furthermore he can use Stirring Up Trouble in high shroud places to flood the bag with these nasty tokens and get some easy clues. Fey is another skill that functions quite well with these kind of spells.
In the end it can only be said if you draw Dread Blessing as your weakness, you could actually call yourself lucky!