Page 25 offers the definition of the character attributes. Specifically, Strength (STR) is defined as "Raw muscle power" and Agility (AGL) is defined as "Body control, speed, and fine motor skills". Based upon those definitions, assigning STR as the primary Attribute for the following makes no sense.
Artisan - Key Attribute: STR (Should be AGL since doing the sort of work defined as "Artisan" require the properties of AGL, not STR. STR can enhance, but it is not essential.
Fighter - Key Attribute: STR (Should be AGL since fighting is far more dependent upon AGL's properties than on "raw muscle power". STR correctly affects damage and which weapons may be used w/o penalty.
Knight - Key Attribute: STR (Should be AGL, See comments about Fighter, above)
Weapon Skill - Axes (STR) should be Axes (AGL). STR affects force applied and whether a given "axe" can be effectively wielded. Hitting where one is aiming depends upon AGL's properties.
Weapon Skill - Blunt Weapons (STR) should be Blunt Weapons (AGL) (see comments about Weapons - Axes).
Weapon Skill - Brawling (STR) should be Brawling (AGL) (Brawling is more bout being able to move and land/avoid blows than it is about the raw power of a given strike. STR can be important when trying to break a hold. AGL can also be very useful when breaking a hold, too (ask a wrestler)).
Weapon Skill - Spears (STR) should be Spears (AGL) (see comments about Weapon Skill - Axes, above).
Weapon Skill - Swords (STR) should be Swords (AGL) (see comments about Weapons - Axes, above).
By this token, however, you could argue that any attribute could and should apply to pretty much all rolls.
For example:
Artisan? It's more about knowing what to do than anything else. Thus, it should be based on intelligence.
Artisan? It's often about trial and error, just keep trying and learning how to do better. Willpower, obviously.
Artisan? Well, you try swinging that hammer for half an hour with a low constitution score.
RPGs have to keep it simple, to an extent, otherwise you end up with overly complex systems that slow to a crawl at the table.
That, and swinging a big piece of metal is very much about strength, as the main things are moving said piece of metal faster than the opponent can parry or dodge it, which is mostly strength, and hitting hard enough that the opponent won't get up and hit you back, which is definitely strength.
Could the case be made that precision is pretty important as well? Sure. But that also goes fo how good you are at evaluating your opponent's reach (which would be intelligence), or how good you are at outlasting him (con), depending on how you're armed.
They went with strength, which is fine as far as I'm concerned, 'cause it applies to most weapons and fighting styles (moving your weapon faster than the opponent is a definite advantage in pretty much all circumstances, both when you're armored and when you're not).