Weapon type does matter for defensive purposes in regards to parry. Swords parry better for example then a dagger or an axe. This is designed relatively intuitively so if you think it would be hard to parry using a whip it probably does not parry well in the game.

Dodge is affected by your dex and your weight. Again this is designed to be realistic, characters that have a high dex and are not carrying much will dodge better then someone with low dex and 100% of there wieght capacity filled. So to maximum dodge, maximize your dex and minimize how much you are carrying.

If you are playing a warrior and are purely looking to maximize defensive capabilities at loweer levels (pre 40) you might want to look at the weapon specialization skills such as the one you mentioned, defensive spin. Sword, spear/staff, and polearm all have a 20th level skill that increases your defense in one manner or another I would recommend reading up on those skills (Flourintine, defensive spin, distance) as they each work differently and would consider choosing one of those specs for any warrior aiming to be more defensive.

My personal favorite defensive oriented warrior is a spear/staff spec felar, though arials would be even more defensive with this weapon spec.