Core/Misc: Reduce differences between cores

Port From (https://github.com/TrinityCore/TrinityCore/commit/ff6a107ac0e7a82d728f8fd2fd8423743233a474)

Source/Game/Entities/Player/Player.Items.cs

@@ -5061,7 +5061,7 @@ namespace Game.Entities
                     {
                         // Do not allow polearm to be equipped in the offhand (rare case for the only 1h polearm 41750)
                         if (type == InventoryType.Weapon && pProto.GetSubClass() == (uint)ItemSubClassWeapon.Polearm)
-                            return InventoryResult.TwoHandSkillNotFound;
+                            return InventoryResult.WrongSlot;
                         else if (type == InventoryType.Weapon)
                         {
                             if (!CanDualWield())

Source/Game/Entities/Player/Player.cs

@@ -243,7 +243,7 @@ namespace Game.Entities
             SetInventorySlotCount(InventorySlots.DefaultSize);
 
             // set starting level
-            SetLevel(GetStartLevel(createInfo.RaceId, createInfo.ClassId, createInfo.TemplateSet));
+            SetLevel(GetStartLevel(createInfo.RaceId, createInfo.ClassId, createInfo.TemplateSet), false);
 
             InitRunes();