As suggested in the title, I ran into Gurt's Greataxe. I was looking up magic items in my free time since I was curious, and I thought why not search for magic items related to greataxes, since my character is a Half-Orc barbarian who is currently a barb-fighter 4-2. I accidentally ran into Gurt's Greataxe while searching, which is offered in the Storm King's Thunder campaign that I'm in with my group. For further information, Gurt's Greataxe gives:
+1 bonus to attack and damage rolls. It is sized for a giant, weighs 325 pounds, and deals 3d12 slashing damage on a hit, plus an extra 2d12 slashing damage if the target is human.
The axe sheds light as a torch when the temperature around it drops below 0 degrees Fahrenheit. The light can't be shut off in these conditions.
As an action, you can cast a version of the Heat Metal spell (save DC 13) that deals cold damage instead of fire damage. Once this power is used, it can't be used again until the next dawn.
Heavy. Small creatures have disadvantage on attack rolls with heavy weapons. A heavy weapon's size and bulk make it too large for a Small creature to use effectively.
Two-Handed. This weapon requires two hands to use. This property is relevant only when you attack with the weapon, not when you simply hold it.
Based off of this rather immense power that the axe has between the 3d12 slashing damage, the extra 2d12 if attacking a human, and the cold version of the Heat Metal spell, although subjective to the DM, what is a reasonable level range that this weapon could be offered in? Because with this weapon, I'd say there's a point where it would be rather overpowered if given too early, and I just needed some outside input on this thought.
If needed, I'm currently running a Totem Warrior Half-Orc Barbarian who's 6'10" and going on the bear path, meaning I can carry double capacity at level 6. Let's say I obtain a strength score of 22, what would the circumstances be then?