I'm going to put my foot down and say this now, removing the "Death Orb" passive is redundant because looking at Umbras's history, BEFORE "The Sacrifice" dropped, he WAS considered a Prime with the introduction of Warframe's China build under the name of "Excalibur Umbra Prime" to which I reiterate, removing said Death Orb passive was somewhat unneeded. Really now Umbra as far as I can tell would simply be a good alternative to those that don't have founder access like others (because I just know the "founders" are gonna start something with this) and GIVES them an Excalibur Prime... without it being labeled as a prime. He is in essence an update to a preexisting prime that truthfully did need a lot more than what he offered because I'm gonna be honest... for a prime, Excalibur Prime was very underwhelming for what he offered. I'd say just put it back because, yes... he IS a prime. An unofficial prime frame but a prime nonetheless.
And I already know I'm gonna get flack from the founders on this so I'm gonna say this now... NO. Hands off the keyboard, you stop right now. Excalibur Prime has already has his time in the limelight. Time to pass that torch to a new Excalibur Prime variant. So drop the salt and don't start anything.