"Splitting the Tree is not natural. It's a preternaturally powerful, preternaturally accurate shot, under conditions that shouldn't work, but do. It's like draconic flight or giantish skeletal systems. Because you have this ability, you are partaking of something that doesn't exist in our world (namely, the martial power source), which allows you to do things that we can't do in our world. However, these actions also have restrictions that we don't have in our world."
Basically, if you're taking a simulationist tack to 4E, then accept that 4E does not support martial power as skill, training, or talent; it is as unnatural as turning undead with a holy symbol or burning them with eldritch fire.
If it doesn't look like a duck, or quack like a duck, it's probably not a duck. None of the crunch of the martial power source indicates that it is actually meant to represent the results of real-world practice and training; therefore, I advise stop assuming that it's supposed to.