It's the only armour-piercing Unique Sniper Rifle in Far Cry 6, which makes it an instant winner, because you really want your sniper rifle to be armour-piercing.
This armour-piercing rifle is pretty much the best sniper in the game thanks to its enormous damage and 10x scope which enable you to one-shot enemies with ease. I usually prefer my Sniper Rifles to be equipped with a Suppressor, but El Tirano is just too powerful not to use. As long as you're a decent shot, you can clear an entire camp of enemies just by standing behind a wall and popping them all one after the other. Combined with the ability to see and shoot through walls, it's just sickeningly overpowered. La Varita on its own is an immensely powerful Resolver Weapon which can one-shot-kill almost any foot soldier with a headshot.
You can obtain both La Varita and Triador by completing the Triada Relics trio of treasure hunts - the most challenging of which you can read about in our Far Cry 6 Oku's Triada Relic walkthrough.
Triador's special ability is to see through walls, and La Varita's special ability is to shoot through walls. But there's a catch: in order for it to reach its full potential, you also need to be using its companion Supremo, Triador. La Varita is by far the best weapon in Far Cry 6.