The first time we see DKs is during Wrath; and then there is a new batch during Shadowlands.
Could a DK have been risen during the times of Cataclysm or Legion??
Yes. In Legion we see new Death Knights risen as troops to send out on missions at the Mission Table. Now whether this is canon or not we cannot say, but we do know that also in the short story before Shadowlands I believe it is stated that Bolvar raised a bunch of Death Knights cause he knew Sylvanas was coming to fight him and he knew he would have to give into the helm of the Lich King, so he wanted Death Knights to be able to stop him.
Now, it wouldnt make sense for the Deathlord to be one of those or would it?
I would say no because the Deathlord title was given to the player by Bolvar during Legion before he started raising those other Death Knights.
I mean if you look deep enough in. There was a character in classic depicting a death knight well before wotlk.
Ah I see
how about during Cata, MoP, and Pandarea?
can a DK be risen during those times and then became the Deathlord?
A banshee raised DKs in cataclysm.
Death Knights can raise other Death Knights.
There were several.
Baron Rivendare is the stand out but you got the original Four Horseman, some of the bosses in old Scholomance were Death Knights. A few rare mobs in Eastern Plaguelands.
In Cata’s Eastern Plaguelands we stop the Banshee boss from Stratholme from turning one of the pally pals into a death knight. There was also Baron Rivendares son who became a Death Knight. He replaced his fathers position in the burning city.
but none of this worked with the ebon blade did they?
No. Both Cata examples listed were part of the scourge remnants in the Plaguelands.
Ebon Blade took a back seat until Legion.
Not during Cata, MoP or WoD.
The Lich King was frozen during this time.