A possible secondary crowbar attack: strong two-handed stab with crowbar tail from overhead, with shorter range than just crowbar fencing but tearing down unarmored human-size NPCs like Alien Slaves and zombies in one hit (head-hits maybe stunning HECU soldiers that wear helmets). Good for stealth attacks on human-height enemies but inefficient against bullsquids, as they're too low and attack rapidly.
I like it :)
Developing my idea further I thought it would be cool to make Gordon lift his arms with the crowbar on key press and strike on key release.
IRL this kind of preparation should enable him to get close enough to the enemy not touching him (as hands and crowbar are not in front of him but overhead) and deal the blow afterwards.
BTW, this way BHL will al last introduce a reason to walk stealthily and not run in HL1!
I imagine the following effects of this blow on enemies (apart from damage):
Zombies, alien slaves - cringe in pain when hit on shoulder, for zombie maybe chop off an arm; instakill in the head.
HECU grunts - reduced damage on shoulders (as they wear kevlar vests as well), standard damage and cringe in pain when struck in the head.
Alien grunts have thick metal armor, so this kind of attack will just slip off.