Klingons are significantly stronger than humans
Umm, Kruge in ST3 was significantly stronger than humans. He was also significantly stronger than
Klingons, impressing his own crew with his muscular build and worm-strangling bravado.
No other Klingon has demonstrated great strength. Worf can be wrestled down easily enough, and Riker lifts heavy objects better than Worf does. There are no outlandish physical achievements attributed to Klingons - unlike all that dialogue that says Vulcans are 3-5 times stronger than humans, the TOS instances where the half-Vulcan Spock throws Kirk around like a ragdoll, or those STXI visuals that show Nero and his men leaping across great distances, lifting humans with one hand, etc.
Klingons probably thus would swing their swords only as hard as dedicated human swordfighters or axeswingers - say, the Vikings of popular entertainment. Any strength advantage would come from there being statistically fewer weaklings in the Klingon fighting force than in a comparable human unit, thanks to the nature of the warrior culture.
Regarding bat'leth practicability, a key feature of the blade is that it provides its own handguards. No Earth sword I know of has a blade with holes cut into it for handholds - the guard is always either a wholly separate construct or then at most a short cross-member near the grip. The bat'leth might be quite difficult to manufacture, actually: how do you cut those three holes into this big sheet of metal? How do you forge such a broad sheet in the first place? Or do the inner and outer arches start out as separate pieces that are then hammered together?
Yet once one
has managed to manufacture that shape, it makes for very good protection for the hands holding the blade, again emphasizing how this is a good weapon for amateur defense rather than professional offense.
One may ask whether the outer arch is sharpened into a blade at all... Do we ever see it cutting anything? We see that part of the weapon being used for pushing the opponent away on several occasions, and there are no cuts in evidence as the result. The modern bat'leth might simply be a warhammer with four pointed ends for piercing the enemy armor, and the front curve would be but a dull shield for blocking enemy attacks by catching his blade.
Timo Saloniemi