It occurs to me that in the Channeler Skills post, I forgot to list a very important ability almost all channelers share; heightened senses related to their element. Unlike many other channeler abilities and skills, this type of sensory input tends to vary wildly from element to element, so it would be best to look at what sensory abilities channelers develop depending on their element.
Air, Water, Earth, Metal: Channelers who belong to these four elements tend to develop the ability to sense the size and shape of something composed of their element that they are touching. If they develop this ability, they can sense the composition of something made of their element, including the particulates and impurities inside it, allowing an air channeler to sense humidity or pollutant contents, a water channeler to sense poison, or earth and metal channelers to sense gems or the type of ore that exists in a metal vein. Eventually the range for this sense increases dramatically, allowing an air channeler to sense the size and location of everything displacing air in a certain area (hidden passages, people, objects, you name it), a water channeler to do the same for underwater areas, an earth channeler to sense the layout of a building or cave system, or a metal channeler to determine the inner workings of a mechanical construct. Another way this ability can manifest is the ability for them to sense their element at range, which can prove very useful for trying to find water, or things buried in the earth, or veins of metal in a mine. If a channeler develops all of these abilities together, they can gain a startlingly accurate spacial sense of their surroundings, even if their other senses are impaired, with air being the most powerful, followed by water (people are water, afterall) then metal (armor and weapons) then earth.
Life: Perhaps the most versatile of the elements when it comes to sensory awareness, life channelers can not only sense the shape and composition of living things (allowing them to eerily diagnose medical problems) but they can also detect the location of living creatures nearby. Further, unlike any of the other channelers, they can enhance their own senses of sight, smell, hearing, touch and even taste to levels that most people might find uncanny or disturbing.
Death: Death channelers share the ability of air, water, earth and metal channelers to sense the location and composition of dead things, but they can also sense ghosts and spirits who have trapped themselves in the inbetween, but have not left for the afterlife. Ironically, with all of their abilities, death channelers make extremely efficient hunters and exterminators of the undead.
Kanna: Kanna channelers develop an uncanny spacial awareness that borders on precognition. Individually their sensory powers are not as developed as any of the other physical elements (due to having mastery over all physical composition instead of a specialized selection), so their ability does not have a very large range. But within their immediate surroundings they may as well have 360 degree sight that is not limited by mundane things such as walls, barriers or illusions. Kanna channelers also have the ability to sense magical items, and intuit the general enchantments that such items possess.
Light and Shadow: These two elements give their channelers an immunity to being blinded, either by light that is too bright, or the darkest of darkness. This ability remains if their eyes are covered or even removed. Development of the ability allows them to sense the dancing patterns of light and shadow that exist beyond solid objects, which can prove extremely handy if these channelers have teleportation powers that require the exit and entrance to be equally dark or illuminated.
Heat and Cold: These two elements develop the ability to sense what is hot and what is cold at a distance. This quickly allows them to not only develop an infravision that works through walls, but it also allows them to develop a mental map of heat and cold for how an area is constructed. Even if two pieces of material are the same temperature, a heat or cold channeler can eventually learn to distinguish one material from another if the materials have different insular properties.
Electricity: The sensory abilities of an electricity channeler can seem like a joke compared to many of the other elements. Their ability to sense electricity at its most basic of levels is not very useful. Eventually an electricity channeler can develop a sixth sense about where people are located (due to the electromagnetic fields of their nervous systems). Practice might allow them to tell if someone is lying or not, though this might not work on all creatures (valdrex, for instance, are probably immune to such lie detection). Otherwise, this ability would probably just let them know if an electrical storm is coming. In a world where electricity is more of a novelty than a viable technology, electricity channelers do not find much use for their extra senses. The static electricity charge on a dry day combined with their ability to sense electrical reactions inside brains might let them develop a spacial awareness similar to the other channelers, but this ability would be vague, indistinct and unreliable at best.
Sound: Sound channelers are experts at detecting sound and vibration. They can use this ability to "see" what they hear, developing a spacial mental picture based on their hearing. Also, similar to light and shadow channelers, sound channelers cannot be deafened, so for the most part, they also cannot be "blinded." A sound channeler who fully develops their power will notice virtually everything there is to be heard, which can make them excellent spies, scouts and information peddlers.
Manna: Like kanna channelers, manna channelers can sense the location and general type of enchantment for magical objects. They can also, with practice, begin to sense the location of souls, be they living or dead. Developing this power to its fullest potential allows them to sense the auras of all physical things (regardless of how faint those auras are) which can give them a spacial awareness similar to that of the kanna channeler, but their ability to do this does not come as naturally as the spacial awareness of a kanna channeler.