The strange looking very large or small numbered sizes are "tall", "stocky" or childrens' sizes.
English language versions of the Uhlmann sizing chart can be downloaded from:
http://www.uhlmann-fechtsport.de/down_g_e.htm
Unfortunately the charts aren't in html but rather are zipped versions of either MS Word or Wordperfect documents.
The sizing chart also can be found printed on the paper insert (the one with the serial number on it) that comes with Uhlmann jackets or knickers. If someone you know owns the same Uhlmann model of clothing you're interested in, perhaps they'd still have the paper version.