Add weapon data

public/data/weapons/hailstone.json

@@ -0,0 +1,13 @@
+{
+  "id": "hailstone",
+  "name": "Hailstone",
+  "atk": 121,
+  "crt": 14,
+  "rarity": 3,
+  "skills": [
+    {
+      "name": "Ice Bullets",
+      "description": "[SP: 14][CD: 13s] Deploys the weapon, firing an ice bullet at a random enemy within range every 1.0s for the next 8s. The ice bullets explode, dealing 521 Ice DMG to enemies in a small AOE and slowing their Attack Speed by 50% for 0.8s."
+    }
+  ]
+}