I think the strict RAW answer would be (as others have said) "an aspect is an aspect" and that mechanically, there are no aspects that are aspect-ier than others. Probably most aspects should be treated as having about 2 shifts of effect. In the examples given, that 16-shift psychomancy should probably have been cast as an attack instead of a maneuver, and if it had would likely have inflicted several meaty consequences or even taken out the target (depending on whether it was a mook or a major character).
If the table decides this isn't meaty enough, one quick answer would be to use the overflow rules. If only 8 or less shifts were needed to inflict the maneuver, then the remaining shifts would be enough to apply a second maneuver, thus double the power. I think this is not allowable per the RAW, though, since overflow can only be used for a non-combat effect, and applying a negative aspect probably counts as combative.
That said, there's certainly room for GM judgement. If a player achieved a 16-shift success on an intimidation attempt (spell or mundane), then invoked the generated aspect for effect, I could certainly see the sense in a GM ruling that the target simply flees due to the resulting compel. But the GM would not be required to rule this way. Of course, if the aspect was tagged for a bonus, instead, it would only be worth +2, as normal.