When Skye is given her powers and spends time in Afterlife, it's explained that she can control the vibrations in the objects around her, with I think some implication that this works down to the atomic level (can't remember that last part for sure). She is shown able to cause an avalanche at the distance of potentially miles, cause massive subsonic waves (I assume that's what we usually see when she fights), vibrate glasses with incredible precision (despite eventually breaking them). Her powers of 'flight' show a high level of control over whatever it is she produces as well, given that the ground suffers no consequences of having a 140 lbs human propelled upwards at ridiculous speeds.
Given these abilities it seems like she should have a wide array of tools to use in combat, especially with other inhumans. Just to name a few thoughts:
Cause massive oscillations within the target's body similar to a microwave, cooking them from the inside
Vibrate the inner ear causing instant vertigo
Stop an opponents heart, which should be much simpler than starting a heart; a task she has already accomplished
Find a resonance frequency with the target's bones to shatter them
Vibrating or heating an object or weapon to make it painful to hold on to, which could also work against clothing items to distract or limit powerful enemies.
Ignite the gunpowder in the bullets in enemy weapons while they are still in the cartridge.
Although her sonic blast seems to work pretty well against regular humans in many situations, there are also a variety of fights we see where alternate tactics would be much more effective against human opponents, and where her sonic blast is flatly ignored by inhuman opponents. This occurs in episodes when she has the bracers designed by SHIELD.
Is it explained in universe why she never seems to use her powers as anything more than a shockwave? And why is the shockwave so limited in strength (it was shrugged off by Lash), when she can channel enough energy to literally bring down a mountain at range?*
- I know an avalanche can be caused by a relatively small amount of energy targeted at the right place, but there was no indication she knew where the right place was and just brute forced it. The earthquakes she causes are further indication that she can release massive amounts of power, as was the moment she took down half a square mile of forest before being taken to Afterlife.
I have only reached S4E5, so apologize if this is explained later and would appreciate spoiler tags for beyond that point.