Cpt Isaac's page

I have a player arguing that since their spell like ability has no components that he can cast it in public and no one can tell that he casted it as their is no visible effect.
The spell specifically is charm.
So my question is. Is their a visible effect to spells like charm and others? Or do they just happen without anyone being able to tell other than the creature freezes up for a moment (Not even as they can still walk with their move action)

It says it increases the threat range of your melee weapon to 19-20. So I want to know what happens when it's used with a 18-20 threat weapon or perhaps a 20x4 weapon with improved critical.