So with the previous version of this thread lost somewhere in both the sands of time and the far reaches of the forums along with the occasional job concept popping up periodically, I figured I'd do a revamped version of explaining my system for job concept creation.
This system is called the ORMOA method, which is an acronym for Origin, Role, Mechanics, Outfitting and Abilities. Everything that defines a class (or job in the case of this game) falls into one of those five components, and every job concept I've made has followed this system. Since the last time I made a thread for this, it was a more generalized version that could be used with nearly any game that bears a class system, but I'll narrow it down more for FFXIV.
Like all of my job concepts, this has been broken down to spoiler text for easier reading.
Origin:
The origin of a job doesn't just give a fancy backstory, but it also provides a reason for it to exist within the confines of the world of the game. For FFXIV, the goal of the origin is to answer three questions.
1) Where did this job become a thing? If you notice in the lore for each job, every one of them has some sort of origin point to a particular nation or region (i.e. Ishgard for Dragoon, Ala Mhigo for Monk, Hingashi for Samurai, etc.), and it would help to brush up on any information about regions both visited and unseen to help gain a better understanding for what kind of jobs would come from where.
2) Why did this job become a thing? Pretty much every job in the game was made as a lore-based solution to a lore-based problem such as combating a threat, protecting the populace or some other means of solving some sort of "crisis". Much like how business requires a problem to sell a solution, a job concept needs a crisis (usually region-based) of some sort to sell the solution.
3) How does this thing reach the main protagonist? The main protagonist in this case is the player's character. How it reaches the character could be a variety of ways from a single character (Samurai) to a problematic scenario (Red Mage) to a representative of a a greater organization (Paladin). Most importantly, when it comes to characters for the origin component, it's best to either remain vague or create new characters; otherwise, do not use main characters of any other storyline as not only does it show a degree of laziness in regard to creative detail, but it's also substantially harder to justify bringing a main character into a minor job story compared to the other way around such as Estinien. Bear in mind that the most extreme devs have done in this regard has been to bring in much lesser characters in for cameos, but nothing beyond that.
If you're going to go the extra mile and make questline story, the best way I've found to think about it is by past (starting level to start of would-be present expansion), present (level range of would-be present expansion) and future (as in general possibilities future expansions). The past would provide insight into the backstory, the present would show some extra background lore and practical application, and the future section would just be a brief overview for how the player could potentially find separate portions of lore that would continue to flesh out the job within the game.
Role:
The role is almost what you think it is. Yes, there is the decision of whether it's a tank, a healer, a melee, a caster or a physical ranged; this should be something straightforward. However, there is also determining the desired amount of utility. Utility simply means what other things a job can do outside of dealing damage and performing its primary role if it is not a DPS job, otherwise identifiable as "buffing" or "debuffing".
Since the last time I made an ORMOA guide back in the days of Heavensward, utility types were more finite between assault-type (almost no utility) to support-type (usually more than three skills or abilities that provide a visual benefit to the group). With Stormblood, this has gone from an on/off switch to a spectrum as a means of ensuring more jobs are not barred from content.
The goal of the role component is to determine not just the fixed role, but also the level of desired utility for the job concept.
Mechanics:
This component is intended to provide a brief overview of how the job would perform its intended role. The best way to think of it is if someone told you to explain the job in under a minute, that explanation in writing would be the intended goal for this component.
Elements to mention would include used resources, how would its job gauge work and any particular unique features it would have compared to other jobs in its particular role. The more you can avoid numbers and listing specific abilities, the better.
Outfitting:
Outfitting simply means what kind of main stat would it use due to its role and therefore what type of gear it would be wearing accordingly.
Unfortunately, Stormblood has created a number of extra limitations when it comes to this component, so it'd be best not to expect mountains to be moved just so a job can exist with a special itemization.
When it comes to weapon choice, it's okay to be creative. Personally speaking, I try to avoid any sort of fluid weapons such as whips or chained weapons just because I know they can be a pain to design, and also avoid gunblades because devs seem to like using more realistic inspirations for most of the attack animations, and gunblades are generally just too unwieldy speaking as someone who has actually been hands-on with one.
The goal for this component is figuring out what its main stat will be (i.e. Mind for healers, Vitality/Strength for tanks, etc.), what type of armor the job would wear and what kind of weapon would it use.
Abilities:
This component is exactly what you think it is: every weaponskill, spell, trait and ability that the job would have. The more detail you list, the better (this also includes descriptions for visual effects as well). Before going head-first into this component though, there are two things that should be done first.
The first thing is to do your research and look at skill and ability lists for the other jobs in the same role as that of your job concept. If it's a tank or a healer, you'll definitely notice a particular set of patterns when it comes to not just what those jobs have in terms of abilities, but what ones jobs get as they level. If it's some sort of DPS, the patterns may be harder to spot, but they'll be there as well. The patterns you find there will make what is easily the hardest part of making a job concept much easier.
The other thing to do is to try to be reasonable when it comes to making skills and abilities. This is another thing that researching other jobs can help with in terms of understanding costs, potencies and cooldowns. At the end of the day, no job is Superman, not even Paladins are entirely immortal, no healer has a trick for absolutely every possible situation, not even Black Mages can kill something just by staring at it, and any job you make shouldn't exceed any of those limitations.
Now that you've (hopefully) read my guide, remember to do your research, try to be a bit reasonable with it, and most importantly to have some fun with it!
Lastly, thank you to those who did read all of this post and those who do post their ideas on these forums.