does effect from rotten winged sword and millicent's prosthesis stack?

[bbhp]

does effect from rotten winged sword and millicent's prosthesis stack? i mean the attack power raising with successive attacks

[bbhp]

i've seen some builds based on it but haven't tried yet. would it work?

[Hakua]

Yes. If you don't believe it, take some twinblades and go test it on the giant @Third church of marika

[Dark■Red ScepTeR!]

Do you wish to join our arena club where we host 3v3s

[Greywander]

The thing is, both are rewards from Millicent's questline, and you can only get one or the other depending on whether you choose to side with her or her sisters.

One option is to just make do with the regular Winged Sword Insignia.

You can get Millicent's Prosthesis without finishing her questline. Give her the Valkyrie's Prosthesis, kill the Godskin Apostle in the windmill village, and she should appear near where the apostle was. This is the earliest opportunity to kill her and get her prosthesis. I believe there's no benefit to finishing her questline if you just want the prosthesis, no additional items are awarded for finishing the quest.

Because of this, if you want to get both items by NG+, then it's recommended to get the Rotten Winged Sword Insignia on NG and Millicent's Prosthesis on NG+. This allows you to assemble both items as early as Altus on NG+, whereas doing it the other way around means waiting until you've nearly finished Elphael.

You can also do a speedrun to get the prosthesis, then trade it to another save file with the help of a friend. You can probably get this done in a couple hours, the only required bosses being Commander O'Neil and the Godskin Apostle.