After partly solving the 2h axe bug, this was the most annoying bug for me then. It took me a whole afternoon to find out where the problem lies in and how to fix them, though finally it appears to be quite simple
So here it is(See attachment)
Installation:
1)download the attachment(descr_walls.txt) or you can download it here:
http://www.twcenter.net/forums/showthread.php?t=74501
2)
a. If you are using the mod switch, simply put this file in your mymod\data\ folder.
b. If you are the unpacker user, then replace the file with the same name in \Medieval II Total War\data directory. always make a backup
c. If you want to play vanilla version, put the descr_walls.txt in your Medieval II Total War\data directory. and create a batch file in your Medieval II: Total War folder. In the batch file add the following line:
medieval2.exe --io.file_first
Save the batch file and then launch Medieval II: Total War using the newly created batch file.
If you have any problem please let me know
for those who are not familiar with this bug:
The ballista/cannon tower in M2TW is bugged.
For ballista towers, they shoot arrows instead of ballista bolts in large city and fire cannon balls in huge city.
For cannon towers, they always fire ballista bolts instead of cannon balls in citadel.
In a word, I bet you guys have never seen a city tower fire ballista bolts, nor a citadel tower fire cannon balls . And it leads to a funny results: huge city even have better defence than citadel, cuz connon tower in citadel won't work.
Now they are fixed.
Edit: It should be compatible with other MODs, since it seems no modder have ever touched this file. And you don't have to start your campaign over again.