Kahekili is the second most-scariest of the three Puu Manamana trails ("Crouching Lion", or Kauhi, being the most scary, "Graveyard" being the "least"). It is an "honest" trail which means it continusly climbs without dropping down (rollercoastering). At no time do you descend along the ridge until you reach the approach into Hidden Valley.
There are a few sections which require some scrambling. The entire trail waivers between slabbing along the slope-side, obscure switchbacking, and following the ungraded ridgeline. It is generally decent in terms of slipperiness and is relatively dry and dusty because of its exposed, dike-rock nature (it drains quickly). However, the dustiness makes it susceptible even the briefest of showers and can make a descent muddy and tricky
Dangers/Other Considerations:
This is undoubtedly an "expert" trail and only those of significant and serious Oahu hiking experience should attempt this hike. Also, as previously warned, this trail is not for the acrophobic!
The main danger stems from climbing up/descending the sometimes narrow, moderately exposed sections with their steep drops (sometimes on both sides). In a few trail sections, very little keeps you from plummeting off the ridgeline. This trail is not a continual "freak-show" and frightful sections don't constantly appear throughout your journey. However, they do exist and you must be physically and mentally prepared for them no matter what skill level you're at or how often these stretches show up.