Don't forget, though, that all player characters generated from Book 1 (all Marine, Army, Navy, Scout, Merchant, and Other PCs) are not subject to that rule--they're all considered to have Skill-0 in all of the weapons listed in Books 1-3 (usual types of weapons--non-exotic or alien).
This doesn't apply to all Traveller PCs. For example, Doctors, from Supplement 4, are subject to the rule.