[quote=@LaXnyd]
As for why Catherine needs Zack to talk to Maka, well, it's because Maka's post included the bit about how only Meisters could talk to their weapons so Catherine will need Zack to tell Maka something calming like "Class is starting" or "she's a teacher." 
[/quote]
As far as I know anyone can talk to a weapon unless the person is in weapon form. In weapon form they are more limited. Also to be one one of Lord Death's weapons they 99 kishin souls and one witch soul. I don't think the need soul perception to find a witch. Not all miesters have it.