Your examples for good hero beating a bad villain in combat are not very good.
I will touch upon each of the three issues you named in depth, and in chronological order:
Martin the Warrior vs. Badrang
You wrote "In Martin the Warrior, Badrang was shaking in his fur when Martin the Warrior completely outmatched him. Though Martin sustained a few wounds, Badrang was scared and unnerved by him. Badrang had the longer and better weapon and the advantage of size, but Martin completely dominated the combat."
Not true. Badrang was confident at first, when he and his horde was winning. However, when he saw that Martin's group was winning, he decided to retreat. While he was sneaking away, he killed Rose. This act caused Martin to fall into a Bloodwrath rage, concentrating on Badrang's death. Yes, Badrang had a better weapon, but Martin was the better Warrior. AND, without his horde to protect him, Badrang, like most bullies, chickened out. Also, size isn't always an advantage- it sacrifices quickness and agility- both of which Martin had due to his small size. AND, though a sword is longer, it isn't always a better weapon than a dagger.
Badrang versus Martin: Attributes
A better weapon- Badrang
A better Warrior: Martin
Motivation- escape- Badrang
Motivation- Revenge/Freedom- Martin
Badrang: 4, Martin: 7
So, Martin VS Badrang- personally, I'd rather fight Badrang.
Jangular Swifteye vs. Marlfox
You wrote: "In Marlfox, an expert assassin was killed by Janglur in one-on-one combat. Janglur was armed with a small sling, and the Marlfox was armed with a double-bladed axe. The fat squirrel beat the expert assassin without breaking a sweat!"
Again, NOT TRUE!!!
Janglur is a skilled warrior, one of the best. Brian said that only those who knew him well were not fooled by his sleepy eyes and body fat. To refresh your memory, Gelltor calls Janglur a coward and tells him he needs an army behind him to fight. Janglur immediately challenged the Marlfox, opening an abbey gate and saying that all he needed to do to escape was pass Janglur. Gelltor tries to cut him down, but Janglur kills him by hitting him in the head with a loaded sling. QED, Janglur is a better warrior, NOT a fat squirrel who beats a Marlfox by chance.
Janglur vs. Gelltor: Attributes
Better weapon: Gelltor (in the sling's defense, it is a good weapon melee weapon, but not as good as an axe)
Better Warrior: Janglur
Motivation: Escape: Gelltor
Motivation: Preservation of honor: Janglur
Gelltor: 4, Janglur: 5
Trisscar Swordmaid vs. Princess Kurda
You wrote, "In Triss, the protagonist beat Princess Kurda easily. The ferret was an expert swordmaster, but an untrained, amateur squirrelmaid beat her hands-down"
Iyiyi! Wher edo you get this info? To quote Brian Jacques, pages 369-370. All emphasis is mine:
It was the first time in her life Kurda had faced a creature that was armed and ready for her. The others had nenevr been a problem. They were usually bound and helpless, and she had always been surrounded by Ratguards to protect her.
Does that make her sound so good when compared to Triss? You may say that Triss had no skill, but
A) She's the daughter of a great sword master
B) Do you think Martin would have given her his blade unless she knew how to use it?
C) Her title is "Swordmaid."
Obviously, Triss was skilled. Also, Kurda was a coward. As Sagaxus put it, again, emphasis mine:
"Kurda lived and died like a coward, running away"
Which brings me to my final point. All triss did was disarm Kurda twice an' break her blade. The Kurda runs away, trips on a root, falls on her sword, and dies. TRISS DID NOT KILL HER.
Trisscar vs. Kurda: Attributes
Better Warrior: Triss
Better weapon: Triss
Motivation: revenge for Shogg and Drufo: Triss
Motivation: Escape: Kurda.
Kurda: 1, Triss: 4.