Special: All base classes except monks, rogues, sorcerers, swashbucklers, warlocks, and wizards have this feat for free. The prestige classes arcane archer, blackguard, dwarven defender, warpriest all receive this feat.
DnD 3.5 comparison
A character could equip a shield without the proper proficiency, but suffered penalties to all skills involving movement and attack rolls
- NWNWiki:Shield Proficiency