Take a look at this;
http://romans-in-britain.org.uk/mil_...le_tactics.htm
I can see how the thrust is more useful but certainly not the only way to use this sword. I find it very hard to believe that any commander would catagorically restrict his troops use of a weapon. However if you are in the turtle I would think your fellow troops would not be fond of you swinging away. So I think perhaps the language may have been too strong or the reference was taken out of context. All in all the book looks intresting, but I think I'll see if it shows up on half.com.