Anyway, I DO have another recommendation in mind. I'm not completely sure if you can call the characters in this series weak, but they are far more uniform in their abilities and are forced to make use of clever strategy due to being put on a more or less level playing field in terms of abilities with those they are up against.
The problem is, I can't remember the name of this series. All I can do is describe it and hope someone else recognizes it from the description.
So, the basic premise is that the earth is being periodically invaded by interdimensional aliens. Essentially, various alien worlds move dimensionally close to earth over various periods of time, and whenever another dimension gets close to earth the races from those other worlds start crossing into earth. Some are humanoid, some are very animalistic.
At any rate, the first key piece of information someone else who knows this series might pick up on is that these alien races are called "neighbors," and the second aspect of the premise is that a completely human-looking neighbor comes to earth and joins the earth defense team. He's a short boy with white hair, and has a special ability that allows him to detect when others are lying. (Can't tell what the truth is, he just gets some kind of ping from his ability whenever someone lies.)
As for the power system in this world, everyone has mana or whatever they call the energy in this world, but they can't manifest abilities on their own. They need special devices to manifest their abilities, and all the devices on earth take the form of guns that shoot special bullets, and there are various but fairly mass-produced and uniform types of bullets all the earth defense agents can get ahold of. One of the more distinctive ones are bullets that cause giant heavy weights to manifest on any surface they hit, which are primarily used for subdual, and the weights take the form of hexagonal blocks of heavy crystal that just manifest as though they're intersecting the limbs and bodies of the person who's hit.
So, anyway, everyone in this universe only has a single ability. The ability to pull the trigger on their guns. The abilities the guns have are dependent on the bullets loaded, and people with stronger mana can just shoot longer or use stronger class bullets. (Well, I mean, there are also non-gun devices that can be used, but the earth defense forces tend not to use those ones. There is a huge preference for the gun-types among the earth forces.)
And, there are occasional additional abilities for people who are very powerful conventionally, but these special abilities are usually limited in scope to something like the boy I mentioned earlier who can detect lies. Yes, the power scale of this world is such that lie detection is considered a very top-class power.
