Skills
Skills, or more accurately combat skills, in this case, are a group of frequently utilized maneuvers, techniques or other means of ascertaining combat superiority or victory over one's opponents. They are derived from each person's knowledge, aptitude and practice, and are often tested in trying situations without proving wanting.
The most important categorization of used skills often proves to be the profession from which it was derived, and more broadly the Fragment that represents it. Those broadly defined categories often have descriptive names, titles or terms attributed to them, and are often used to differentiate a class of opponents - close-range warriors or pyromancers, for example - which is quite important for survival.
Jinx
Jinx utilizes Spells, although contrary to typical Elementalists he can use Fire, Air, Water and Earth with impunity. Additionally, he can combine different Elements with a special type of skill that is tentatively called Synthesis by those who have witnessed it.
Colleen
Colleen utilizes Techniques, focusing on the common skill groups of Shield Mastery, Sentinel and Retribution, although she has dabbed into the monastic discipline of Meditation.
Blood
Blood uses a very... unique collection of combat techniques he endearingly calls Tricks, and breaks them down to the more appendage-specific Savage Claws, Vicious Maw, and Body Building. No one has seen his Underhanded Tricks and lived to spread the word about them.