Thank you for your support!
Just bought the game at gog.com and it also crashes the same way.
It's ver. 2.65.1 and has no drm. Sacred2.exe is 2 824 328 bytes.
The problem seems to be at line 5392 of weaponpool.txt here:
mgr.addWeaponPool { -- NPC_flame_staff
dbid = 1220,
prefDmg = 1,
prefDmgProb = 0,
content = {4278,},
contentProb = {1,1,},
}
when I delete this single element everything works perfectly.