Becoming a vampire lord and getting bloodcursed arrows after curing Serana

Question

I've finished Dawnguard and chose to cure Serana of vampirism, but now I think I'd like to have the option of become a vampire lord and getting bloodcursed arrows. I've done some basic console fiddling but was unable to faithfully reproduce a vampire lord transformation (adding the vampire lord spell turns you into a weaksauce version that dies in 2 hits on Master). Mods and console commands welcome, though I'd prefer something along the lines of Valerica taking on Serana's "duties" or simply turning Serana back into a vampire lord.

Answer 1

Late answer, but there are 2 ways to become a vampire lord:

1. Accept Lord Harkon's gift during the Bloodline quest
2. Receive it from Serana after Chasing Echoes quest (which in your case you can no longer do unless you reload a previous save)

Source - unofficial Skyrim wiki