Add weapon data

public/data/weapons/mitternachts-waltz.json

@@ -0,0 +1,17 @@
+{
+  "id": "mitternachts-waltz",
+  "name": "Mitternachts Waltz",
+  "atk": 287,
+  "crt": 19,
+  "rarity": 5,
+  "skills": [
+    {
+      "name": "Arrows of Verurteilung",
+      "description": "[SP: 0][CD: 0] Use the bow to aim and shoot (max aiming duration: 3s), dealing 650.0% ATK of Lightning DMG. Hitting an enemy weakspot creates an explosion dealing 200.0% ATK of Lightning DMG. The weapon active's CD and charging time are based on the shooting mode."
+    },
+    {
+      "name": "Overture of Nightfall",
+      "description": "The weapon active marks enemies hit for 10s and make them take 125.0% ATK of bonus Lightning DMG. 30 times max (CD: 0.1s). Marking CD: 16s."
+    }
+  ]
+}