It is likely French. Surnamedatabase has an entry on Guichard, stating it is from Wighard. This would give it the same meaning as Wighard.
http://www.surnamedb.com/Surname/Guichard
We have an entry for Wighard here.
http://www.behindthename.com/name/wighard/submitted
These kinds of names originate from Ancient Germanic tribes in which a nomadic warrior lifestyle was the norm, thus the "brave warrior" meaning.