Rulebook says "You may use either hand to make an attack. Attacks made
using your secondary hand suffer a –20 penalty to any
applicable Test. "
Thats for attack. Rolling defense is not an attack roll, why do people say shield is -20 penalty?
Shield dont give -20%
So if you want to be nerdy about it, you do not need to use the shield to defend, only be wielding it (you can defend with your primary weapon)
Defensive
Defensive weapons are designed to parry incoming attacks. If you are wielding such a weapon, gain a bonus of +1 SL to any Melee Test when you oppose an incoming attack.
This would be consistent with the new wording on the Shield Quality in Up In Arms
Shield (Rating): Any time you Oppose an attack you benefit from additional AP equal to the Shield Rating. If your weapon has a Shield Rating of 2 or higher you may also use your shield to Oppose incoming missile shots in your line of sight. This means that you may use a melee weapon in your
primary hand to oppose an opponent’s melee attack at no penalty and gain the AP benefit of the shield in your secondary hand even though you did not specifically use the shield to oppose the attack.
But if you have to actively use the shield to defend (e.g. to block a missile attack) the offhand penalty comes into play
Defensive
Defensive weapons are designed to parry incoming attacks. If you are wielding such a weapon, gain a bonus of +1 SL to any Melee Test when you oppose an incoming attack.
This would be consistent with the new wording on the Shield Quality in Up In Arms
Shield (Rating): Any time you Oppose an attack you benefit from additional AP equal to the Shield Rating. If your weapon has a Shield Rating of 2 or higher you may also use your shield to Oppose incoming missile shots in your line of sight. This means that you may use a melee weapon in your
primary hand to oppose an opponent’s melee attack at no penalty and gain the AP benefit of the shield in your secondary hand even though you did not specifically use the shield to oppose the attack.
But if you have to actively use the shield to defend (e.g. to block a missile attack) the offhand penalty comes into play