Weapon/Ability Name: description
- elemental affinity(ies) (assumed to be non-LMNTal unless otherwise stated)
- power factor (usu. "average;" this is assumed to be average unless stated otherwise, and it is the weapon's/ability's innate power, which is factored with your stats in damage calculation)
- power determinant(s) (what stats of yours, if any, are used to determine how hard it hits, and what stats of the target, if any, are used to determine how hard they take it)
- secondary effects (piercethrough, DEF/RES pierce, armor pierce, status ailments, secondary strikes and their properties, option effects, conditional effects, additional or lesser KB or flinch factors, waterfall damage, split damage, draw-in magnitudes, homing capabilities, tracking capabilities, targeting limits, cutscenes, recoil damage, et cetera)
- ability type(s): physical (standard hack-and-slash plus physical explosions, beams, and basically everything normal to real life; STR versus DEF, usually), magical (MAG determines magnitude, usu. against RES; can also be used for spells that confer a status effect, metaphysical (supernaturally manipulated physics, such as standard elemental manipulation, magically summoned explosions that deal physical damage, supernatural techniques that call physical beams from the sky with the swing of a blade, a spell that both deals magical damage and enacts a physical effect, and more; damage calculations vary), or null (flat-rate damage, disregarding pretty much everything, though the user's offensive stats are likely factored in)
- cost(s): If this is an ability, the cost, such as a moderate amount of MA, needs to be blatantly stated, usually at the beginning or end of the description. If you're tacking a cost onto the usage of a weapon, such as recoil damage or charged attacks (the kind in which you spend MA, HE, MS, PS, or something else with an otherwise normal attack to power it up or give it a secondary effect), the cost(s) should be listed either on the ability that allows you to do this or the abilities that it applies to. If it can apply to normal, physical attacks, the former is recommended.
Steel Shortsword MkII: 30 PWR, non-LMNTal
Flametongue: 30 PWR, fire-LMNTal
Against Leilani, these swords will hit equally. She doesn't take extra or lesser damage from fire, so the fire affinity means nothing to her.
Choh Lehko, however, is weak to fire. When she takes a hit from the Flametongue, the damage that the Steel Shortsword MkII would have done is multiplied by her weakness.
A power factor of a weapon isn't numerically measured on Sein, although you're free to use your own system to show differences between your weapons if you'd like. Dycedarg could say that his Runeblade has a power factor of 35, while his Chirijiraden has a power factor of 40, for instance, and he'd say that 30 is average by his system, so his weapons are good, despite the fact that he's just not strong enough to do them justice. If you don't say that your weapon has a different power factor (See Tixxi's weapons for some examples, like her staves.), it is assumed to be average for its weapon type. That is to say that an otherwise unclarified greataxe is stronger than an otherwise unclarified slim lance, which is stronger than an otherwise unclarified shortsword, but they match the average power factors for greataxes, slim lances, and shortswords, respectively. That goes for all weapons: Their power factors correspond to their compositions. That means that a one-of-a-kind weapon, one with a totally unique design, will be assumed to have a power factor that simply corresponds to the physics of how the weapon works. Basically, use common sense to figure out what weapons are stronger than others unless you specifically set them otherwise. You could have a weak axe and a weaker hammer, but have an amazingly strong knife, for all that I care, as long as you write them that way.
The power determinants are simple. When you swing your sword, the damage formula usually goes something like this (See the optional guide on damage calculations for further explanation.):
(attacker's STR * weapon's power factor * attack's power factor) / defender's DEF * placement factor * ([243...267]/255)
That's not to say that you can't use a different formula; that's just an example of the default formula for physical weapons. In the case of many spells, it would be:
(attacker's MAG * attack's power factor) / defender's RES * placement factor * ((243...267)/255)
Noticing a pattern? If you don't say anything special here, a weapon will be assumed to follow the former equation, while a spell will be assumed to use the latter one. What if you want your weapon to deal damage that's based on how well your target deals with magic? Great. Simply say that it deals magical damage (read: damage that is determined by RES). Want your magical to deal physical damage? Say so. If it deals damage that's based on DEF, it's physical damage. Simple, right? Right. Just be careful that you don't entirely overstep some boundaries, here. A mage that has designated STR as a weakness and MAG as a strength, but can use a spell to deal tons of physical damage has effectively negated a large, combat-relevant portion of its supposed weakness (i.e. the ability to deal substantial, physical damage, though it is still ineffective at the other boons of STR). It's okay for a mage to have access to physical damage, but not to the point at which STR is a 90% safe dump stat.
If you're looking for an example of a null attack and null damage, think of Sonicboom from Pokémon. No matter who uses it on whom, it always deals 20 damage. No stats of the target are counted, so it's null damage. Those whom have played Crisis Core: FFVII will note many null attacks from it. All of the DMV attacks deal their damage even to targets who are invincible to physical and magical damage; the DMV attacks are null attacks, since they nullify any would-be defenses. The Costly Punch materia also grants the ability to perform the strongest attack in the game (up to 32 times as powerful as a normal attack!), and, when you use it, its damage calculation ignores everything but Zack's STR. Although his STR is factored, and although it looks like a phy attack (I mean, you watch Zack rear back and punch downward in a huge haymaker. That's about as physical-looking as it gets.), it's a null attack. There are enemies in that game that always nullify physical and magical damage, and you can use Costly Punch to wipe them out. Null attacks are great, aren't they? Don't get your hopes up too high, though; null attacks are incredibly rare and often difficult to use. Don't expect me to allow many of your attacks to be null attacks for no real drawback.
Costs can be divvied however you want them to be. If you want an ability to take half its cost from your MA and half from your PS, go ahead. If you want 9/10ths of the cost to be to your MS, 1/20th to be from your PS, 1/40th to be from your HE, and 1/40th to be from your MA, make it so. You have to establish the costs beforehand, though; you can't say that you can cast Haste to give someone the corresponding status effect for a small enough MA cost when you make your list, then think of the cost as negligible in battle. If you cast it 100 times and your char has below average MA, an admin is going to step in and say something along the lines of, "Dude, what the piss?" You can have other costs, of course: Charge times, cooldowns, ending lags, recoil damage, or other secondary effects that detriment you can be used. Like I said, though, you have to set those ahead of time. On that Haste example, you can't pause and charge for a few seconds to cast it with no cost unless you already have that option written into your list. Now, you can have flexible costs; you could have, say, an ability with a moderate cost that can be divvied into MA or PS at your char's will. If you're exhausted, you can just spend the whole cost in MA to make it happen, and if you're hale and hearty, but low on MA, you can invert the previous cost. You can have an ability with a moderate MA cost, but give yourself the option of charging it up to reduce the cost by, say, 1/6th of its original cost for every three seconds of charging. You can have different combinations and whatnot. Just remember that whatever you say in your list is what it is unless you train/obtain something new to make it otherwise.