In 4e a defined ability for an acrobat to reduce falling damage could be with a very minor allowance be tweaked to help an ally very easy improvisational change apply a mild skill check penalty or allow the player to spend a utility power slot... and just call it done. And if we are going beyond one of the basic skill functions there are level and resource regulated examples which are available for comparison (no hunting through dozens of classes with things defined in different ways with different resource systems and use cost/frequencies)
I suspect you are not the only one who does not know how to make things not step all over the toes of spell abilities and class features and so on. Improvising fair balanced ability in such an environment is chaos.