Yes it is included. Here’s the formula. Credits to @Kascly
{[(PA+SA)x1,5]+CA+EA+ETD}x(Epee 20%~140%)x™x(ENHANCE)
PA = Physical attack
SA = Skill attack
CA = Critical attack
EA = Elemental attack
ETD = Enemy type damage(damage against medium, large, beast, mutant…)
TM - Target Modifier
The holy attack would be in the Elemental attack so yes it gets multiplied by Epee.
IMO you should still craft other Rapiers, just so you’d have an extra when Venier breaks. 
Seriously, I fought Marnox and both my Venier and Spada broke. Not to mention SP pots, I have like 70-80 level 15 and they were not enough. But we were only like 15-20 people fighting it.
EDIT : For reference I only have level 4 Composee (2 base + 2 from Venier)