<img src="/ubbthreads/images/graemlins/div.gif" alt="" /> is a bit odd when it comes to one-handed/two-handed weapons. Unlike most RPGs with a similar type of interface, if you equip a two-handed weapon it doesn't remove the shield from your second hand, it just greys out the shield and makes it unusable.
I believe Isorun is correct that Slasher is always two-handed. In fact, I don't remember there being even a SINGLE one-handed axe in <img src="/ubbthreads/images/graemlins/div.gif" alt="" />. I could be wrong, of course.
Pretty much, if you want to use a shield, you'll have to find a new weapon that only takes up one hand. (Only easy way I know of to check if a weapon takes one hand or two to wield is to equip it and see if your shield greys out)
