The weapon script system uses the server file..
Data \ Weapons.mts
Create that file on the server and edit using a text editor - 0.1.29 clients and above will automatically download and parse the file when they join.
To check and debug your script, you can use the command
.reloadweaps 1
(Um : Mit (or someone), Edit this and insert the corrent name for the command that i've forgotten - coz i dont think its reloadweaps :])
If there are any lines not understood by the parser they'll be printed on the client chat display.