Just as a general rule (not a detailled or system-based thing, just a hard and fast rule), Kirra and I have discussed several points which would be relevant to the "difficulty" associated with certain abilities doing certain things. That general rule is as follows (unless Kirra decides otherwise):
-If it increases effect, it increases difficulty.
-If it increases range, it increases difficulty
-If it represents a versatility, a general benefit, or any given increase to the character's ability, it increases difficulty.
What this actually means for a freeform roleplay system (since we have no dice, no stats, etc) is that we want everyone to be aware of their own power level, and of how much they're doing with that power. The more you do, the harder it is to do it, and that's just a general fact. We're trying to establish a sort of unwritten rule to govern that. Part of my job as Co-GM will be to voice my opinion whenever a situation occurs which might fall under that rule.
For the most part, it's just about balancing and fair play. If you play your character the way you described in your accepted CS, you have nothing to worry about.