My question to Nigel was:
"The Spear guys have a defense of 10* at some levels. I didn't find a reference to what that means -- can you enlighten us?"
and his reply:
The * by the def 10 on the Spears' card is an error!!!!!
EDIT: and from the forum:
The * in the 'def' column on several Troop Cards shouldn't be there So please ignore it and we'll all pretend like it doesn't exist.