The ghosts start spawning much slower after you complete Lyphia&Evelyn's part (i.e. get to the last event point, where they disappear).
As for beating the remaining ghosts: go to the second room (so you can use the feather), put 3 tanks on the front (they will be perma-charmed), and shoot away with casters (long-range like Kohakuren and Crayanne will be good).
Also, if you have enough Dark resist, they won't use Charm Touch at all. X will obviously work, don't know about S+. So block the way with Sharty/Rags/any on the main characters with Nyx gems, equip them with anti-Dark necklaces, and do as I wrote above.

items are your friend, skills too.
your running out of SP and units are charmed buy yourself a FUCK-TON of hp potions SP potions and clarity powder (removes charm) from the church, hell if you can, buy blood of revival x 100.
And as worldendDominator suggested dark resist is helpful. mutated demon necklaces, yuela and servalwis dark armor equiped with nyx gems (dark resist gems) and if its only dark and physical dmg they deal ragsmuena should be able to tank the lot of them while u snipe em from a few squares away.
make use of everything u can, hard mode is hard for a reason

that ones not even the hardest of lyphia and evelyns missions

on a side note ( and know this was done on normal mode) i teleported wil up to lyphia and eve with kohakurens "displace" skill

ViolatorVash, you can't use items on that map.

I agree for the items but... WorldendDominator just answered actually. I also used Kohakuren displace skill but it's harder to hold the monsters away without some guys.
I will try to build Dark Resist and it will be ok, I guess.

Thanks for your help.

oh shit i wasnt aware >.<

in that case i suggest using the eushully angels equiped with the mutated demon necklace. make sure they have the angels guardin skill and keep them in a square this way they should ignore 2 attacks each combat round.
try and use similar cover skills like shartys "flighty guardian" and wil and the main heroins all have cover sklls for eachother by upgrading their armor.
holy weapons. & if by chance you have a weapon with the "forcefield" should help against charm

should be more helpful this time

Even with Guard skills, a single successful Charm will likely lead to perma-Charming due to sheer number of the ghosts. Unprotected melee is not really an option.
And Forcefield will not be effective there - Charm Touch is point-blank magic (not to mention you can't realistically get Legendary Hammer at this point).

true however not a single attack should get through. keeping the angels in a square formation would lead to dodging 2 attacks and at lvl 70 the combat round should be iin the players favour ( player 2-3 attacks vs enemy 2 attacks) & equiped with the nightmare necklace theyre dark resistance becomes x
that plus the angels have a holy weapon. anything that comes at them should die.
i think its a pretty solid approach

Actually, I have one question left.
You said that Lyphia&Evelyn have to get to the last event point to stop the fast respawning, but I did one event point, killed all the monsters, but there was no new event point.

Well, maybe not. I just read it somewhere.
Although there should be at least two event points for them. Make sure you activate the points with Lyphia.

Finally made it.
Actually, the second event point appears when you get to the Queen of Souls' room.
I destroyed everything with Yuela and her Dark Knight Armor + Divine Blue Fang, she got killed by the boss but I just had to bring Eliza to finish it off.

Thanks for your help.