RPG Developer Bakin

[JayRay]

good question - 

a.eatk is actually the attribute Attack power, which can be put in the equation. This is based on the attirbutes (fire, water, holy, etc.) which is set in the first column. This formula can be independant, based on weapon. 

a.atk is a character's physical attack power
a.mgc is a character's magical attack power. (This might work well for a raw elemental attack that doesn't use any specific attribute.

And you can use an AND/OR idea within your damage formula to only use a magic attack power, only a physical attack power, only the attribute attack power, a combination of one, or the other, whatever you decide.

Also as previously stated an item can utilize the power of a skill within it. ALSO, with a little bit of work with the database, one can add multiple types to an emeny fairly easily, which can be affected by your weapon and its specific damage type. Here is a video on just how that's done.