I wonder which is the most effective dagger of the bunch based purely on design?
Well, the effectiveness of each design would be varied depending on what you're using it for, just like the saying 'if you judged fish for the ability to climb trees...'.
First dagger is clearly a parrying dagger. It excels in stabbing moves, can do a little bit of slashing but if you're gonna punch enemies, it'll leave a mark. This dagger design put emphasis on mobility and defense, making it all-rounded purpose-wise.
Second dagger is slashing dagger. All offense, no defense (since that large fin-shaped spike on the back would've made it awkward to guard if you're wielding it reverse-grip). The design choice is...questionable; those serrated edges won't hold long in actual battle with armored opponent, so this dagger would've served as weapon of choice for petty thieves and bandits for intimidation tactics.
Third dagger is just blasphemy to weapon design. It was meant to be a primarily slashing dagger, but that off-spike on the blade would cause it to be stuck on the flesh, not to mention the hilt was made by intertwined strands, which means it'll be very hard to clean when blood seeps into it.
Fourth dagger is a general use hunting dagger. Simple in design, the main point was durability and ease of use. Slashing, stabbing, bashing, you can do it all.
Fifth dagger is modeled after tantos. Mostly slashing/stabbing attacks, but you can't really parry heavier weapons with this otherwise you'll risk warping, or even breaking the blade.
Sixth dagger is another absurd dagger. An all-offense no-defense thing with how thin the middle section, it would definitely warp after hitting something harder than flesh, unless some harder-than-steel magical metal was used in the construction. Slash-only.
Seventh dagger is surprisingly simple. It's generally a stabbing dagger, given the short blade edge and construction, but you can use it for slash attack, albeit it would deal only grazing wound.
Eighth dagger is another example of parrying/stabbing dagger. Wide blade with wavy edges means you can catch enemies' blade and redirect it, and when used to stab it'll leave wounds with large openings, making it easier to be contaminated with germs.
Ninth dagger is slashing dagger. Aside from fancy ornaments, it really don't have anything to offer.
Tenth dagger is parrying/stabbing dagger. Just like the first one, but with more emphasis on catching a swung blade. The knuckle guard in this one is unattached to the pommel, so while you can use it to punch enemies, it could warp and bend (which is a problem, really, since it could've snapped in the weak middle part).
Eleventh dagger is a ceremonial dagger. You'd sell this and get better dagger, really.
Twelveth dagger is a stab dagger. Nothing much needed to be explained, other than the awkward gear crossguard that makes it hard to grip.
Last dagger is primarily slash dagger. From the small protrusion near the end of it's hilt, this one was meant to be used in reverse-grip style.
So with all that, the conclusion.
If we were to set the danger level to 0 and assume you're just doing practice slashes against a dead pig carcass:
8th dagger would've been best for stabbing attacks.
13th dagger would've been best for slashing attacks.
Well, the effectiveness of each design would be varied depending on what you're using it for, just like the saying 'if you judged fish for the ability to climb trees...'.
First dagger is clearly a parrying dagger. It excels in stabbing moves, can do a little bit of slashing but if you're gonna punch enemies, it'll leave a mark. This dagger design put emphasis on mobility and defense, making it all-rounded purpose-wise.
Second dagger is slashing dagger. All offense, no defense (since that large fin-shaped spike on the back would've made it awkward to guard if you're wielding it reverse-grip). The design choice is...questionable; those serrated edges won't hold long in actual battle with armored opponent, so this dagger would've served as weapon of choice for petty thieves and bandits for intimidation tactics.
Third dagger is just blasphemy to weapon design. It was meant to be a primarily slashing dagger, but that off-spike on the blade would cause it to be stuck on the flesh, not to mention the hilt was made by intertwined strands, which means it'll be very hard to clean when blood seeps into it.
Fourth dagger is a general use hunting dagger. Simple in design, the main point was durability and ease of use. Slashing, stabbing, bashing, you can do it all.
Fifth dagger is modeled after tantos. Mostly slashing/stabbing attacks, but you can't really parry heavier weapons with this otherwise you'll risk warping, or even breaking the blade.
Sixth dagger is another absurd dagger. An all-offense no-defense thing with how thin the middle section, it would definitely warp after hitting something harder than flesh, unless some harder-than-steel magical metal was used in the construction. Slash-only.
Seventh dagger is surprisingly simple. It's generally a stabbing dagger, given the short blade edge and construction, but you can use it for slash attack, albeit it would deal only grazing wound.
Eighth dagger is another example of parrying/stabbing dagger. Wide blade with wavy edges means you can catch enemies' blade and redirect it, and when used to stab it'll leave wounds with large openings, making it easier to be contaminated with germs.
Ninth dagger is slashing dagger. Aside from fancy ornaments, it really don't have anything to offer.
Tenth dagger is parrying/stabbing dagger. Just like the first one, but with more emphasis on catching a swung blade. The knuckle guard in this one is unattached to the pommel, so while you can use it to punch enemies, it could warp and bend (which is a problem, really, since it could've snapped in the weak middle part).
Eleventh dagger is a ceremonial dagger. You'd sell this and get better dagger, really.
Twelveth dagger is a stab dagger. Nothing much needed to be explained, other than the awkward gear crossguard that makes it hard to grip.
Last dagger is primarily slash dagger. From the small protrusion near the end of it's hilt, this one was meant to be used in reverse-grip style.
So with all that, the conclusion.
If we were to set the danger level to 0 and assume you're just doing practice slashes against a dead pig carcass:
8th dagger would've been best for stabbing attacks.
13th dagger would've been best for slashing attacks.
4th dagger would've been best for general use.
lastly, 1st dagger provides the best defense.
Well, now I know what blades I'll be taking on my epic. Thanks!