One thing I've noticed is that, in RPGs, there are many types of abilities and items that tend to show up late in the game. For example, in Dragon Quests 2 through 5, the game will eventually give you items that let you heal for free. (You also see this in Early Final Fantasy games.) Other examples include things such as revive abilities (especially those that restore full HP), sacrifice heals (kill caster to heal the rest of the party), instant death attacks, and other effects of similar magnitude.

Every once in a while, however, there's an RPG that breaks the rule and gives you such things early in the game. This thread is about those things. Now, however, there are a few rules for this thread:

1. The ability or item must be easily acquired by a casual player without going way out of the way or heavy grinding. ("Heavy grinding" is far more than is needed for a casual player to survive.)
2. The ability or item must not use up a rare or non-renewable (at that point in the game) resource. For example, something like an early Megalixir does not qualify here.
3. The game must not take it away. Hence, abilities that a temporary character gets do not count. (For example, in FF4, Tellah's spells do not count, even though he gets spells that are far stronger than what you would expect to get at that point in the game.)

Anyway, here are some examples that I have found;

Dragon Quest 6: When Chamoro/Nevan joins your party, he comes with a weapon that, when used, casts Healmore/Midheal/Behoimi (depending on translation) for free. Note that chances are that nobody else in the party has a healing spell that powerful (and anyone can use it). This happens relatively early, before you even get access to the game's class system. Something similar happens in DQ7, except that the item is weaker (only Heal/Hoimi), but it does come at a time you will be glad to have it.

Phantasy Star 4: Rune comes with a Wood Cane, which heals 32 HP for free when used. While Rune is only temporary, you can unequip this weapon, and then everyone can use it as an item.

Paladin's Quest: Early on, the game gives you the Sph Cr (Sophie's Crown), which heals the user 800 HP when used for free. (For comparison, Midia has less than 200 HP at this point.) Only Midia can use it, but since she is a permanent character (with only one scene where she is absent after you get her), it counts.

Phantasy Star 3: Just look at Mieu's techniques. There are some rather fancy ones available, including:
GIRES, which heals the entire party.
REVER, which revives at full HP (but can fail). Can even be used out of battle by a dead character!
FORZA, which instantly kills a biological enemy. (It works like VOL from PS2 and PS4, and you *do* get XP.)
NASAK, which, if successful, kills the caster and fully heals the rest of the party. (Hint: Try combining this with REVER.)
Also, with a reasonable amount of grinding, it is possible to afford the Force Vest, which, when used, casts REVER for free (and can be used outside of battle). Note that Mieu stays in your party between generations, so you have these abilities permanently (though FORZA is useless if your main character is Ayn). (Also, the Royal Vest casts a reliable NASAK, but I think it is too expensive to get at the first opportunity, unlike the Force Vest.)

Final Fantasy 5: You get the Staff of Healing, which casts Cura (Cure 2) when it hits, early in this game. In fact, you get it before you get the Cura spell in the first place! Also, the Blue Magic spell Vampire is an HP drain attack that you can get *really* early. Also, with the !Mix ability a Chemist can learn, you get a full revive earlier than you would expect. It requires a Phoenix Down, which is expensive but fortunately not rare, to use, and it even restores MP.

SaGa 3 DS: The two weakest long swords in the game have an instant kill attack that you can learn. In fact, it is likely that a player will learn this before reaching the miniboss at the top of the first tower and instant kill the miniboss with it; it happened to me when I was playing the game.

Since you mentioned healing, in Morrowind one of the first quests will net you a healing spell gadget. Ring or something.

In Terraria, I think every generated world has a sort of shrine place that will net a powerful blade weapon. Just a matter of digging down to get it. Go early enough and you've then got a powerful weapon that'll carry you quite far through pre-hardmode.

There is a similar hidden ring in Oblivion but it can be a bitch to find. As soon as you get out of the dungeon you need to haul ass across the map and get to it before it slips into the ocean. Later in the game it's useless but it's very nice right at the beginning when the rest of your stats are so low.

Final Fantasy 8 is laughably broken.

In Baldur's Gate, I remember there being a cloak early on in the game that you can steal, that has unlimited uses of Charm Monster or something.

Descent 2 had a helix cannon well-hidden in the second level.

Creating a "bag" in the original C64 Gold Box version of Pool of Radiance. Pilling up the max amount of arrows and then splitting it a number of times eventually created something called a "bag" that could be loaded in your bow doing a tremendous amount of damage. Wonderful when i was a kid playing this game. I found it pre-internet cheat sheets by sheer happenstance so I will claim it casual.

Does the alien blaster in Fallout count? I think it is down to luck whether you meet the special encounter which grants it to you, but I don't think there is anything stopping you getting it very early in the game (if you are lucky). I think all you need after finding it is that you get your energy weapon skill high enough to use it effectively, and enough money to buy energy cells (ammo) for the gun. It helps if you had tagged the energy weapon skill and put points in it already on character creation.

I think it is considered to be the most powerful weapon in the whole game, also because you can fire it two or more times per round. Yeah, quite often it would destroy enemy with one shot, especially if you were able to hit an enemy in the eyes with it. It is highly accurate too, but the only downside is that its range isn't the greatest (so the best tactic is to run close to enemies and shoot them in the eyes, or waiting around the corner so the enemies have to come close to you, and then BLAST THEM).

It's not THAT easy. 1 shrine in small worlds, 3 in medium worlds and 4 in large ones, and only a flat 1/3 chance of finding a decent sword per shrine (so, 66/29/20% chance of not finding the sword in a world at all). Finding the shrine requires overland travel, which can be risky, and they're hard to see.

An easier one is Starfury, a sword found in floating islands chests. The sky is relatively safe and easy to get to with a 60s sickle, the islands are obvious, and the chance of finding the sword is +1/4 per floating island (so if your world has 4 or more, you're guaranteed a sword), which are themselves more numerous (up to 4/6/8 in a world).

In Demon's Souls I got the Demonbrandt, which is like the second most powerful sword in the game, really early around level 30 or 40. I don't think I had finished any of the 5 areas by that point.

Granted the game doesn't exactly give you the sword, you have to fight Old King Doran for it, and he can kill level 80-100 characters in one hit. But those games are all about being smart, not strong, so if you do know how to work things in your advantage, only go for backstabs, and are very patient and persistent, you can get this great weapon very early.

I used a similar strategy for Havel's Ring in Dark Souls, although that fight wasn't meant to be quite as difficult.