I do 
Like @DaVice said, it depends on the weapon that you craft with said edgesmith and also on the target you are planning to fight with said weapon…
An edgesmith has a 1.222 modifier on Armor Penetration
As a comparison, the bladesmith has 1.06
So again, like DaVice said, it is a percentage bonus of the original armor penetration of the weapon.
What does that mean?.. That if you want a big armor penetration bonus, then you have to craft a weapon that already has a decent amount of it on.
If you take the Obsidian Hammer, which has the third highest armor penetration from basegame weapons and the best from the craftable ones. (other 2 being Blade of 7 winds and World Breaker)
it has a base damage of 51 and armor penetration of 51.75%
- if you use a bladesmith to craft the same weapon, you will get a weapon with 63 damage and 54.86% penetration
- If you use an edgesmith to craft that weapon, it will result in a weapon with 54 damage and 63.24% Armor penetration so gaining almost an insane 11.5% (definitely not 1%)
If you then proceed to hit a target with that weapon… and the target happens to be… a fairly armored one… like maybe the Rhino boss, sporting 7500 armor
Hitting it with the first Light attack opener. That one has a modifier of 1… so it does the full damage that’s written on the weapon. (let’s ignore strength bonuses and such for simplicity)
The Rhino boss’s damage reduction clocks in at 93.75% from the armor value mentioned above
- Weapon A from the bladesmith sporting 54% penetration but 63 damage will hit the Rhino king for: 36.34
- Weapon B from the edgesmith sporting 63% penetration but 54 damage will hit the Rhino king for: 35.39
And due to how Armor mitigation is a curve and tones off (even before this level), there isn’t a target in the game where the edgesmith would lend a significant advantage, even the Arena Champion, sporting 19k armor will take 35.3 damage from the bladesmith one and 34.6 from the edgesmith one 
It’s obviously going to perform way worse on non-armored targets. Like going up against your average Cimmerian Berserker, who’s sporting a lovely 479 armor, providing 48.91% damage reduction
Weapon A (bladesmith): 49.09
Weapon B (edgesmith): 44.29
Frost Giant at 122 armor, 19.61% reduction
Weapon A: 57.42
Weapon B: 50.1
Etc.
Conclusion:
While it is not a bug and the stat is working as intended, I agree that it’s not balanced and poor edgesmith cannot really compete with the others due to how armor penetration was reverted back to the old multiplicative formula with Age of Sorcery.
It could probably use a buff
probably even as much as a 1.56 modifier instead of the 1.222 (which puts it on par with the bladesmith vs a target with 50% damage reduction in case of this Obsidian Hammer if everything else stays the same, still less effective for other weapons)