The game also allows members of Vanargand to use elemental alchemic attacks akin to “casting spells”. These ragnite catalysts vary in effect ranging from dealing damage to an enemy or an area, healing your allies, buffing them, etc. Activating them consumes RP (Ragnite Points) which can be recovered by using items or by using basic attacks. These spells have different ranges and area of effect which you can see after selecting the spell and before activating them.
Technically, any characters can equip any elemental ragnite. Aside from the class restriction, a character’s proficiency or rank to a certain element will also determine whether he or she can equip the ragnite crystal. For example, a character with a Fire Rank 5 can equip any non-exclusive fire ragnites Rank 5 or below while a character with Water Rank 1 can only equip non-exclusive rank 1 water ragnites. The exception for this however are Galdrs or ancient spells that only Ophelia can equip and use.
Ragnite crystals with higher rank doesn't always mean that they're better than the low-rank versions. While it is true that higher-ranked crystals have more base stats, you also need to toggle the description to see if the crystal you want to replace has extra effects. It's not worth trading off a lower-ranked crystal with one or two extra effects to a high-ranked version that only gives you a meager base stat increase with no extra effects.
Character elemental ranks and max RP can be increased by upgrading the Mana Engines of their weapons through Basil’s Factory. Mana engine upgrades consume ragnite crystals so don't sell your old and outdated ragnite crystals. You can use it to power up your character weapons and unlock more skills and elemental ranks. Take note that the elemental ranks will still vary per character; some are just more proficient with a specific element or two which allows them to enhance their main element further, enabling them to equip even more powerful ranked ragnite crystals you’ll get later on.
You can get new spells by buying them from the Ragnite vendor in Promenade, as battle spoils, and by exchanging shards in Godot's Exchange option in the HQ. Shards can be acquired as free DLC and reward for off-mission objectives.