Add weapon data

public/data/weapons/betrayer.json

@@ -0,0 +1,17 @@
+{
+  "id": "betrayer",
+  "name": "Betrayer",
+  "atk": 245,
+  "crt": 15,
+  "rarity": 5,
+  "skills": [
+    {
+      "name": "Treason",
+      "description": "[SP: 18][CD: 12s] Launches 6 homing missiles in a row, each dealing 200% ATK of Physical DMG to the target an nearby enemies in a small AOE. Hit enemies are stunned for 2.50s."
+    },
+    {
+      "name": "Betrayer's Counter",
+      "description": "When attacked, gain a 50% chance of dealing 160% ATK of Physical DMG."
+    }
+  ]
+}