[X-Script]

I'm not sure but I found something close, I couldn't find anything to check the weapon the player just bought. But what you can do is check if the player is in the buyzone cs_get_user_buyzone and then check what weapon he has and if it's a glock or usp then don't do anything but if it's something else like a AK47 or M4A1 then do what you want to do.

But if you find out how to detect it, then don't go with my suggestion.

get_user_weapon