Pat swordfish steaks dry with paper towels. Season both sides with salt and black pepper.
Heat a large heavy-bottomed skillet over medium-high heat. Add olive oil and heat until shimmering.
Place swordfish steaks in the hot skillet without overcrowding. Sear for 3–4 minutes per side until golden brown and opaque inside (145°F internal temperature).
Add minced garlic and lemon slices to the pan. Cook for 1 minute until garlic is fragrant and lemon slices slightly caramelize.
Squeeze juice from remaining lemon half over the steaks. Remove fish from pan and transfer to plates.
Sprinkle chopped parsley over the swordfish and serve immediately.