Alright since I'm planning to have 7 Strength so I probably won't be down right awful at shooting it. :tops:
When I hear "requirement" I usually think that means the bottom line to use, I guess in this case its the bottom line to use at the most effectiveness.
If Fallout 1, 2 & Tactics are anything to go by while you can use a weapon which has a higher strength requirement than your own strength, you get penalised for each point of strength you are below the requirement, so to use the quoted comment you can still use the weapon but not quite as effectively as you could if you had a strength of 8. I would go as far to say that while you won't be as effective you won't be down right awfull with it, I think the down right awfull would be if you tried to use it with a strength of 4 or lower especially with a low firearms skill in conjunction to that.
Back to the topic at hand, if you look at the light, medium & heavy armour types in the historical PnP (Pen and Paper) RPG context, then the likes of your leather armour will fall under the Light category, Combat Armour probably Medium, Metal Armour may be around the low Heavy or high Medium and Power Armour is definately Heavy Armour. Basically the more protection and more restrictive to your movement an armour is the higher up the 'grading' it is, at least using the definition set I mentioned.
Or to look at the armour 'weight/protection' categories another way, you could say that Light Armour equates to little/no protection or 'Mummy he's got a peashooter, I'm gonna die'. Medium Armour is reasonable protection or 'Hah he's got a 9mm, do your worst and I'll survive'. Heavy Armour is High/obscene protection or 'Ohh he's got a minigun, I could do with a nice refreshing lead shower'
The 'comments' are meant to be somewhat tongue in cheek to try to highlight the differences between the armour types in a somewhat overblown way.