This is mainly to change the sound when swinging the weapon/lightsaber. 

I meantioned weapon because this also affects the swing sound for the machete and cleaver so if you don't mind those weapon sounding like this then go ahead.

For this you will need SFX Manager
You can just look for this tool in the tools section in gtainside.com.com

https://www.gtainside.com/en/vicecity/tools/

Step 1
Open the SFX Manager

Step 2
On the top left part click "Open"

Step 3
Go to your GTA Vice City folder and for the Audio folder

Step 4
Once inside, most likely you will only see sfx.SDT since it only reads that file then double click it.

Step 5
Be patient since it may take some time to load but mostly only seconds will do.

Step 6
On the SFX ID Column, look for 171,172,173 since this are the sounds you need to replace.

Step 6.1
Before doing this, always make sure you have a back up of the sfx.SDT file just in case you want to change it back. I will create another Read Me If You Can if you want to replace a specific sound.

Step 7
On the top part again you will see like a 'CYCLE BUTTON' which says "Replace". You need to replace one by one.

Step 8
Highlight the SFX ID you want to change then click replace(BTW once you highlight something you hear what sound it represents on the game)

Step 9
You can now select the specific sound you want to change it with but make sure that the file name is still the same like for SFX ID 171, the file name should be sfx00171 and so on.

Step 10
Once you double clicked on the file to replace it with it may take sometime again so make sure to be patient so that the tool will not crash. 
(This might take a little bit longer but mostly not reaching 1 minute.)

Step 11
Once you are done replacing all the sounds you want you can now hit "SAVE" and just wait patiently again so that the program won't crash.

Step 12
Congratulations!
You now have the the Lightsaber Sound Effect.