Powerful Imagination

A child's mind is a terrifyingly, powerful, thing.

As a young being, you are graced with a Magical Imagination that spurs you to action with magics, legendary weapons, and the greatest of defenses.
But it all comes at the cost of your innocence being the target. Where you believe you are strong vs some things, you are also weak vs others.
Should you become too knowledgeable, you 'Grow Up' and Lose this Feat and it is replaced with an Ability Score Improvement.***

Pros:
Whatever item you wield as a weapon, and as your armor, gains a +2 Magical enchantment.
If its a Magical +1 weapon, it is now +2 to the wielder, and maintains any other properties. (Example: Fiery Sword/Blade)
If the weapon is a stick, the wielder can 'believe' it to be a sword, and it can do slashing or piercing damage.
Whatever clothing you wear is now +2 and magical, Shields included.
If it was already magical, it maintains any enchantments, and now also has +2 enchantment.
These items do not require attunement.

You also believe yourself to be resistant to some elements as they simply 'bounce off you' like they are nothing. You aren't immune to all of the damage however, but you can wade through a field of fire, weather the biting and bitter cold, or find the acid to just 'not be that bad'.
Gain Resistances to 2 of the following choices: Fire, Acid, Cold, or Lightning.

Your magic comes from your very imagination, whether healing magics, or a raging fireball, you are the one that manifested that outcome through sheer will.
You can be a Godless Cleric or Paladin, or a Patron-less Warlock; but having, or gaining, a Deity or Patron just further grounds your character's imagination, and changes nothing.

You cannot be killed outright in 1 attack, if you would have died from an attack or ability, become Dying instead.

Cons:
You are but a child, and your abilities stem from a lack of understanding, and strength, as compensation.
While the world is your oyster, you have not yet learned enough to comprehend it all, and you don't fully realize that with understanding more comes with a heavy toll.
Your Strength, Intelligence, and Wisdom are at 8.
Should you push Intelligence or Wisdom  to a 10 or higher, you 'Grow Up' and lose this feat as it becomes an Ability Score Improvement immediately (even in the midst of combat).***

Just as you are mighty vs some elements, there are still things out there that scare and impair you. These things hurt more than others as they bypass your Imagination's capabilities to overcome them through sheer will.
Gain Weakness to Two of the following: Psychic, Thunder, Poison or Necrotic

If you fall unconscious, or are Dying, this feat, in it's entirety, is disabled until you are awake again.
If you become scared or frightened, or mentally impaired by an ability, this feat is disabled until you regain your confidence or the ability wears off.
The clothing or 'armor' you wear is no longer enchanted with a +2, and you lose your weaknesses  and resistances.