Hussar
Legend
The Balor's hands are full, one way or another. He can't control three weapons at once.
He's not attacking. He doesn't have to control them. He just has to hold them. Are you honestly saying it's impossible to hold two swords at the same time? Note, he doesn't have have to hold it to teleport away. He just has to touch it. Heck, he stands on the sword and teleports away and it comes with him.
This is exactly my point. In these conversations, the counter arguments are based on such bizarre readings and interpretations. Lines of sight measured out to a mile? Sure, if your outdoors looks like a golf course. A 3 foot rise with 2 foot tall grass on it gives 100% concealment. And cover. Our Balor has 120 foot vision. Teleport into the party, (because I can see you before you see me) use my surprise round to fly 30 feet in the air, grab the wizard with my whip, hit him with my sword, fly another 30 feet in the air and let go. Dead wizard before the fight has even started. Fly away and repeat the tactic a few more times, killing the cleric next.
Only issue here might be, can the balor turn off his own flames. That's not in the book, AFAIK, so, this tactic would rely on a DM saying that he can control his fire aura.
Or, hey, it's a balor. Why not have some burning pits scattered around the room? There are a million things that the DM could do here that would make this fight extremely deadly.
But, yeah, when your fights are in empty arenas, then sure, the party is going to be a lot stronger.