Add weapon data

public/data/weapons/mjolnir.json

@@ -0,0 +1,17 @@
+{
+  "id": "mjolnir",
+  "name": "Mjolnir",
+  "atk": 298,
+  "crt": 6,
+  "rarity": 5,
+  "skills": [
+    {
+      "name": "Wrath of Thor",
+      "description": "[SP: 18][CD: 13s] Drops a hammer of thunder that knocks down enemies, dealing 405% ATK of Physical DMG and impairing them, decreasing their DEF by 80% for 4.00s."
+    },
+    {
+      "name": "Crush",
+      "description": "Gain 15% Crit Rate."
+    }
+  ]
+}