This thread probably will be updated a bit more frequently, given that some of this info is undocumented or at least not looked into enough.
Each weapon has a spell power similar to using Wis/Will/Enemy Magic rating, except it is calculated against the Weapon's "Spell Power". I am unsure
how this value is stored/interpreted internally... it could be a simple number that is actually the "Spell Multiplier".. or a number that is calculated against.. like Weapon's Spell Power/4.
Anyways, onto the data.. I will also list what the number could be stored internally is pretty much in the range for (Spell Power * 4 to Spell Power * 4 + 3). You can derive the damage if you attack Imps/Goblins with the magic (Imps/Goblins have 0 magic defense). I will provide some notes to what you see on the screen... although very few weapons exhibit special effects.
All Status Inducing Equipment = 255 or 0 (I dunno what value is stored)
Rod = 1
Note: Attack image is of a "grey fist attack".
Ice Rod = 2
Flame Rod = 3
Thunder Rod = 4
Stardust Rod = 7
Lilith Rod = 8
Cure Staff = 2
Note: Cure Staff healing is split like a Summon spell... it uses the base and multiplies it against the "modified" and weaker Cure spell..
randomized for each target.
Flame Spear = 4
Blizzard Spear = 4
White/Holy Spear = 2
Dancing Knife = 8
Note: Think Rod animation, but replace fists with knives.
Poison Axe = 0
Earth Hammer = 1
FF4A only
Asura's Rod = 2
Thor's Hammer = 7
Triton's Dagger = 7
We have EVEN MORE themes now, but some old ones are gone...