There is only one type of fabrial in this set, informally known as the Alerter. An Alerter can warn one of a nearby object, feeling, sensation, or phenomenon. These fabrials use a heliodor stone as their focus. I do not know whether this is the only type of gemstone that will work, or if there is another reason heliodor is used.
In the case of this kind of fabrial, the amount of Stormlight you can infuse into it affects its range. Hence the size of gemstone used is very important.
Reports of the Assassin in White's odd abilities have led me to some sources of information that, I believe, are generally unknown. The Windrunners were an order of the Knights Radiant, and they made use of two primary types of Surgebinding. The effects of these Surgebindings were known-colloquially among the members of the order-as the Three Lashings.
This type of Lashing was one of the most commonly used Lashings among the order, though it was not the easiest to use. (That distinction belongs to the Full Lashing below.) A Basic Lashing involved revoking a being's or object's spiritual gravitational bond to the planet below, instead temporarily linking that being or object to a different object or direction.
Effectively, this creates a change in gravitational pull, twisting the energies of the planet itself. A Basic Lashing allowed a Windrunner to run up walls, to send objects or people flying off into the air, or to create similar effects. Advanced uses of this type of Lashing would allow a Windrunner to make himself or herself lighter by binding part of his or her mass upward. (Mathematically, binding a quarter of one's mass upward would halve a person's effective weight. Binding half of one's mass upward would create weightlessness.)
Multiple Basic Lashings could also pull an object or a person's body downward at double, triple, or other multiples of its weight.