3 turn damage calculation with buffs on, I will just be using the max dmg as calculation since it makes it easier
150816 - 184219 np1 bride 9.14% refund
9895 - 11982 second position arts 23.60% refund
11461 - 13896 third position arts 30.45% refund
6813 - 8216 third position quick 9.62% refund

OC2 1 stack of bride def buff:(damage changes)
169605 - 207184 np1
11069 - 13418 second position card
12831 - 15571 third position card


94494 - 115381 np1 saberlot 4.48% refund
31831 - 38794 second position arts crit 30.21% refund, 25.73% w/o NP buff on and 26609 - 32412
37053 - 45176 third position arts crit 39.18% refund, 33.20% w/o NP buff on and 30961 - 37730
18046 - 21945 third position quick crit 15.74% refund

tama/waver team, all NP up, skills up, assume saberlot card crit and bride don't
nero bride route:
turn 1:
fox's wddding + waver attack buff + bride buff(normally you pop this when you get 2 arts card, but this is a 3 turn calc)
waver NP + bride OC2

choices, bride1 means she has a arts card this turn so we use, bride2 means she has no arts card this turn so we don't use and use tama's Np instead

bride1: bride has a arts card, so we use this turn
refund = 9.14% + 30.45% = 39.59%
tama NP this turn will get it to 60%+, bride can NP again next turn.
so we have at minimum 2 NPs, one with 184219 and another with 207184 and one arts card
minimum damage dealt = 405299 here

bride2: bride has no arts card, we use OC3 tama NP
refund = 9.14% + 37.5% = 46.64%, if one arts card 2nd/3rd position here will gen 20% to reach 60%, if not you won't

saberlot route:
turn 1:
same as bride route pop your buffs and tama fox wedding and waver's attack buff
waver NP>OC2 saberlot NP then depending on whether arts card is here

if yes: saberlot1
if not: saberlot2

saberlot1:
arts card is here with 80% arts buff,
we gen 4.48% + 33.20% = 37.68%
same position as bride, tama NP will bring us to 60% next turn
so we have at minimum 2 NPs, one with 115381 and another with 115381 + 1500(OC2) + 45176(arts crit) + 1500 = 278938

saberlot2: tama NP
we get to the 40% threshold, this means we can self charge to 60% and have waver do first charge + waver defense to 100%,
we will again arrive at the same as the damage above
one with 115381 and another with 115381 + 1500(OC2) + 45176(arts crit) + 1500 = 278938

as you can see the difference between each saberlot's card critted vs bride's card non critted is 31k after both OC is applied(using 3rd position arts card bonus)
45176 + 1500 - 15571 = 31105,
but the difference between 2 NP + 1 arts card damage is already
405299 - 278938 = 126361 which means you have to already crit on 4 more cards in that rotation to outdmg her.

As you can see unless bride does not get a arts card on turn1 and does not get a arts card on turn 2, saberlot cannot catch up in dmg rotation

in addition as you saw, def down increases damage way more than +1500 dmg add, this means in each rotations later, the damage will stack up more

if you want to say what happens if merlin was here instead of waver, saberlot actually already provides 15 stars with skill + 6000 weight, so he will be able to crit on his own

on the other hand merlin would actually boost bride more with crits since we assume bride does not crit.
bride can gen 47.20% on second arts card and 60.90%