Add weapon data

public/data/weapons/arc-serratus.json

@@ -0,0 +1,17 @@
+{
+  "id": "arc-serratus",
+  "name": "ARC Serratus",
+  "atk": 275,
+  "crt": 32,
+  "rarity": 5,
+  "skills": [
+    {
+      "name": "Void Bullet Hail",
+      "description": "[SP: 18][CD: 18s] When scoring a hit, deals 500% ATK of AOE Physical DMG and impairs enemies (-40% DEF) for 12s. Wielder gains 5s Iron Will buff: greatly increased Ignore Interrupt and each Combo ATK decreases target's DEF by 4% (CD: 0.4s. Max stack: 5) and refreshes the duration of the impair debuff."
+    },
+    {
+      "name": "Iron Will",
+      "description": "When Iron Will is active, wielder gains 50% Crit DMG and 50% Shield DMG. When Iron Will ends, gain a 6s Iron Legacy buff. When Iron Legacy is active, if the wielder exits the battlefield, the whole team gains 40% Melee Crit DMG for 12s."
+    }
+  ]
+}