Alundra 2 has a quest to gain the most powerful sword in the game, where you must do a Trading Quest all over the world.

Plus, if you piss off the ATF, you cannot repair your relations with them. You then need to escort the crippled ship out of Terran space while every ATF ship tries to gun your prize down, then get to try and equip it with the rare and expensive Terran weapons, when the Terran economy is in an eternal state of collapse unless the player props it up. On the other hand, the only way to acquire ATF ships (until Albion Prelude) was to, ahem, ' permanently borrow' them, which is no easy task when every ATF ship is part of a massive flotilla of ships, and ATF ships are the second most heavily reinforced ships against boarding, almost as much as the Xenon capital ships, so boarding them requires a huge investment in marine training and an expensive Missile Frigate for its Boarding Pod. ATF ships are capable of stomping almost every other comparable ship, due to their combination of speed, shielding, and raw firepower.

AGI Task Force ships in X3: Terran Conflict.

Getting it requires you to finish the main plot, then laboriously gather up weapons to fit it with - it can't mount standard Commonwealth or Terran weapons, only the Aldrin prototype weapons - which often requires manually resupplying the factories due to a shortage of traders in the system where the weapons are produced. It's faster than any fighter except the Aldrin Spitfyre, has the shielding of a small capital ship, and has the cargo capacity required to kill capital ships by either Macross Missile Massacre or Death of a Thousand Cuts from ammo-consuming guns (most weapons are Energy Weapons).

The Aldrin Springblossom corvette in X3: Terran Conflict.

Also, it's unlikely the dungeon the sword is in will be uninhabited in fact, the monsters there tend to be very XP-rich anyway.

One would think that the time needed to finish the subquest could be better spent on Level Grinding, so the Infinity +1 Sword is often more useful because it has other associated stat bonuses, unique to the character, rather than merely being stronger than other weapons (or so strong that even leveling up can't give you that kind of strength). If you want it, you've got to put the plot on hold and embark on a five-hour sidequest! That, or find the enemy that Randomly Drops it (which will likely be a Metal Slime or Boss in Mook Clothing from the Bonus Dungeon, and the drop rate may be just 2 percent, or 5 percent with a Random Drop Booster).

So you'll never get it by just sticking to the game's main story. This is a weapon, spell, special attack, etc., that is not only the most powerful of its kind in the game (at least for its respective player character(s)), but its power is matched by how hard it is to acquire.

Aika online skill simulator level 99