The blood elves and the night elves don't seem to have directly clashed often even after Quel'Thalas officially joined the Horde. Obviously the blood elves right now are likely considerably stronger than the night elves, given what happened at Teldrassil and their additional losses in the Battle for Darkshore, the Fourth War, etc.
And yet, I wonder, hypothetically, if they both fought each other at some point in the past (perhaps just before Battle for Azeroth, for example), and there was absolutely no external interference or assistance, which side would most likely have emerged victorious.
There are five points to consider:
- The blood elves successfully fended off night elf spies in Quel'Thalas in the past, killing several of their best rogues.
- Lady Liadrin noted that, "Tyrande is a Sentinel. She knows little of war on this type of battlefield. While her scouting is useful she should recuse the Kal'dorei from the main assault. My blood knights are the only ones prepared to carry the weight of this conflict.
- The blood elf rogues such as Lorash were extremely effective in killing night elf Sentinels and druids - he was able to swiftly kill Anaris Windwood, the leader of the Sentinels in Ashenvale, and then easily killed nearly an entire group of druids in Ashenvale (their home terrain) despite their best efforts to subdue him.
- The blood elves have access to the blood golems and the full power of the restored Sunwell; their mages seem to be far more advanced and proficient than those of the kaldorei, even with the Highborne backing the latter. They are also the most experienced Horde race regarding paladins, and Quel'Thalas had Silver Hand members even before blood elves existed. The night elves have not really used the Well of Eternity, except maybe in their restorative moonwells, nor do the Wild Gods / Cenarius seem interested in directly assisting them any longer.
- Tyrande and Malfurion are indeed far stronger than Lor'themar, Halduron and Rommath, individually and possibly even together; however, the blood elves are probably cunning enough to disable them somehow if they put all their efforts to the task (Tyrande was nearly slain by several Horde archers in Wolfheart, and Malfurion was defeated by an axe thrown by Saurfang at Darkshore).