Amsel,
The Stielhandgranate was primarily used as an offensive grenade, without the fragmentation sleeve, relying on the concussion effect to kill or subdue the enemy and not so much shrapnel. But since this was its' primary function it also meant that the explosive charge needed to be larger than in a defensive grenade in order for it to be effective. However the Germans simply supplied a thick metal sleeve to be put around the explosive container turning the offensive grenade into an even more lethal defensive grenade. (The British had a similar design, the No.69 offensive grenade, also supplied with a fragmentation sleeve if the situation demanded it)
Mostly the Stielhandgranate was used without the fragmentation sleeve, which would've made it less lethal than a defensive frag grenade, explaining what you've read.
As for the explosive charge:
Soviet RGD33: 80 gram
US Mk.II: 57 gram
German Stiel. Hdgr.43: 168 gram
British Mills Bomb: 71 gram
German Ei.Hdgr.39: 112 gram