Mundane Traits define your character and improve their capabilities, but not in ways that would be particularly exceptional.
Put another way, a Mundane Trait would differentiate a body builder from a runner, but would not say if that body builder can lift a full-size ox or if that runner can make a 3 minute mile.
You are not considered when attacked by surprise if no other circumstance would make it impossible to defend yourself. However, your attributes are considered to be -1 during a surprise attack.
Your limit is 50% higher and the speed penalties for being encumbered are halved.