Biography
Some characters are graced with great strength that they never bother to hone: they are Unskilled, but Strong. Other characters have little strength, and compensate with amazing ability and skill: they are Weak, but Skilled.
Then there are characters who are both Strong and Skilled.
There are multiple possibilities here. The Weak, but Skilled characters got an Upgrade Artifact, so now their impeccable poise is impossibly puissant. The Unskilled, but Strong characters decided to train (maybe using a Power Nullifier), giving their fantastic force a fatal finesse. Those characters who have The Gift can only use said power by improving their technique. In an interesting twist, Hard Work Hardly Works is wrong for these characters because all of their innate abilities or powers could only be fully accessed with a lot of training. Or the characters simply have both skill and strength.
The Strong and Skilled characters are likely to surprise enemies because You're Nothing Without Your Phlebotinum is untrue; they can only be Brought Down to Badass. They may be weaker but they're hardly useless, much less unthreatening. As a villain, they'll be at or near the absolute apex of the Sorting Algorithm of Evil. As a hero, they probably are a Showy Invincible Hero who takes all fights seriously.
In anime and comics, they are often The Mentor, The Rival, or just a hopelessly powerful Big Bad. In a video game, they'll probably be That One Boss who has a good AI and ungodly stats/powers. For a PC they may go from the Jack of All Stats to the setting's strongest Lightning Bruiser, bar none.
Compare Master of All, who is great at everything; Badass Bookworm, who is both a fighter and a thinker, but not necessarily the strongest one of the lot; and Genius Bruiser, who is both a thinker and a fighter, but not necessarily a genius about fighting. Contrast Well-Trained, but Inexperienced, a character who may have skills but lacks the real-world experience to use them properly. Sister Trope to Talented, but Trained. The goal of Boxing Lessons for Superman.
Overlaps with Stronger Than They Look if the characters look like they're just Weak, but Skilled.