From what I understand, using scripthook basically only spawns the 3D models for weapons rather than as actual active weapon objects.
On the topic of the pool cue;
http://gta.wikia.com/Pool_cue
"In GTA IV, the pool cue is in fact been categorized as a weapon alongside other melee weapons but the use of the pool cue as a weapon was dropped during development. The pool cue may still be used to play pool but cannot be used outside the game, even though it's a functional weapon.
In The Lost and Damned, however, a broken-off version of the pool cue can be used as a weapon. Additionally, pool can still be played. However, it disappears from the player's inventory whenever a race is started, as the player is given a baseball bat. Also, the pool cue has no dodging animation which only allows the player to block attacks and also makes it impossible to do melee counters in a fight."