Here's some data that you could look over.. I'm not posting HP ranges at those levels because it would not be a fair comparison (but also because I'm lazy atm).
The data here is assumed that the character is totally unequipped.
DK Cecil @ level 10 (initial)
STR: 13
AGI: 10
VIT: 11
WIS: 6
WILL: 3
Paladin Cecil @ level 1 (initial)
STR: 10
AGI: 13
VIT: 10
WIS: 5
WILL: 8
As you can see, there is not too much of a difference initially.
There's a range between two different levels at which I will be comparing Cecil against, just to make my point.
A realistic early level that Cecil will be at before becoming a Paladin is level 17. A late level would be more along the lines of level 27.. these numbers are used to maximize the attack multiplier (which is very important in the damage calculations).
His stats after equipping the Deathbringer Sword (which is the FF4A name or Death Sword in FF2 SNES)
Deathbringer adds +5 to STR, AGI, VIT, WIS, and -5 to WILL
Data in parenthesis are unequipped stats.
Level 17:
STR: 24 (19)
AGI: 19 (14)
VIT: 20 (15)
WIS: 13 (8)
WILL: 1 (2)
Cecil will have an attack multiplier of 5x with a defense multiplier of 3x (when a shield is equipped).
Level 27:
STR: 32 (27)
AGI: 25 (20)
VIT: 25 (20)
WIS: 16 (11)
WILL: 1 (1)
Note: Stat min cannot go below 0 and there is a wraparound for stats lower than 0 to the value of 1. This is slightly different in FF4A where the wraparound is only "displayed" as 0 for stats lower than 0, but internally the negative stat loss is factored in.
Cecil will now have an attack multiplier of 6x with a defense multiplier of 4x (when a shield is equipped).
For Cecil to even remotely compete with the DK at level 17 in terms of the attack multiplier... he needs to be at level 23 (I like 24 though since he learns Heal/Esuna).
None of Paladin Cecil's equipment at this point boosts his STR in any way, so that's part of the flawed comparison that some idiots make when they say Cecil as a DK is radically stronger than Paladin Cecil (assuming you hacked it so that DK Cecil is always there in the party).
Level 23:
STR: 24 (24)
AGI: 17 (17)
VIT: 23 (23)
WIS: 13 (13)
WILL: 33 (18)
Note: The Will Power boosts are coming from the Paladin equipment you buy at Mysidia, assuming you are using them in conjunction with the Legend Sword.
That will produce an attack multiplier of 5x with a defense multiplier of 3x (assuming you are using a shield).
The thing is that it really does take a while for Cecil to rebuild his STR to "reacclimate himself" to Dark Knight levels. When Dark Knight lovers forget to factor in that Paladin Cecil is far more versatile and stronger once these stats are properly rebuilt...
There's also these reports or "claims" that Dark Knight Cecil is weaker than Paladin Cecil in terms of the monsters. This is true, but only for one reason. All the Paladin equipment you buy
has Undead Resistance. Cecil as a DK is not that bad when facing the undead, he's just won't properly compare favorable for those that like the Paladin more (like I do).
These are distinctions worth pointing out, and hopefully that answers your question better.
In sum:
DK Cecil only appears stronger in terms of attack power than Paladin Cecil
at the time of conversion.
DK Cecil has a stat boosting weapon (Deathbringer) which completely makes comparisons against Paladin Cecil very unfavorable. DK lovers make these silly comparisons.
Paladin Cecil is on par, if not stronger than DK Cecil, when the Paladin reaches level 23
for enemies that are not weak vs Holy elemental since the Paladin starts with a Holy elemental weapon. Only one enemy on Mt. Ordeals is not weak against Holy and doing damage calculations against Holy elemental enemies totally screws the comparison. Paladin Cecil is pathetic in dealing damage prior to this level, especially when trying to kill Ravens.
Paladin Cecil is defensively stronger than DK Cecil vs Undead
only because the equipment has Undead resistance. This issue is negated when he's off Mt. Ordeals.
It will take a long time before DK Cecil will have a Magic Defense Multiplier.. whereas it takes far less time for Paladin Cecil.
Hopefully that answers the question you have with this information.
