Critical hit only effects the tile damage from the specific hero with the specific troop, and the bare knuckle hits from a defending teams hero with the specific troop…
doesnt it seem kind of weak in comparison to the higher %damage and the significant mana boost from the other 4* troop type?.
One guess is that they are balanced vs each other in some beta-situation when critIcal hit hade a wider Spectra of what it applied to. (specials,dots etc), and when it got tuned down the damage% werent compensated to balance for the new value.
Could it be something to look into?.. maybe raise the damage% on crit troops so the gap between the two troop types arent so distinct.
As of now they are equally rare to get but one is significally better than the other.