Blackened Swordfish

We know, blackened food went the way of the disco ball years ago, right? Wrong. It makes for a really succulent fish, try it.
1 teaspoon salt
1 teaspoon minced fresh thyme
1/2 teaspoon dried oregano
1/2 teaspoon cayenne pepper
1/2 teaspoon sweet paprika
1/2 teaspoon ground black pepper
1/2 teaspoon fennel seeds, crushed
4 6-ounce swordfish fillets
2 tablespoons olive oil
4 teaspoons butter
Preheat oven to 400°F. Mix first 7 ingredients in small bowl. Place fillets on baking sheet. Brush on both sides with 1 tablespoon oil. Sprinkle top of each with seasoning.
Heat heavy large skillet (preferably cast-iron) over high heat until very hot. Add remaining 1 tablespoon oil; swirl to coat. Place fillets, seasoned side down, in skillet. Cook until very brown on bottom, 1 minute. Return fillets, browned side up, to baking sheet. Place in oven; bake until just opaque in center, about 8 minutes. Top each with 1 teaspoon butter.