A few points;
1) Typically a vest should be armor 2 vs piercing, armor 1 vs a few other things such as crushing and light slashing attacks. It should not work against fire, poison, medium and heavy slashing attacks, most explosions and most magic. You'd need to find some serious armor to work against most things and have heavy armor. For example, a nanofiber full suit with ceramic strike plates, insulation and a breathing mask would be armor 3 vs most things... but it would cost a couple hundred $.
2) The armor stunt explicitly
stacks. So someone with that or a similar stunt that wears a vest would get the bonus from the vest AND the +1 from the stunt. I tend to use that on my zombies. Give them a "no blood" stunt for +1 armor vs piercing and slashing attacks and have them be policemen or soldiers with bulletproof vests. Hilarious.
3) A fae, lycanthrope, scion, vampire, dwarf, demigod or other variation of supernatural with "toughness" abilities can get something like this;
[-4] Supernatural Toughness
[+3] Catch; nephilim are vulnerable to either silver (because it represents purity, which they do not) or poison (because it represents mortality, which is their failing). Choose either one or the other.
I hear it is especially appropriate for demigods. Especially for demigods of battle.
@compelling aspects;1) No, you can't just randomly compel an aspect or randomly apply an aspect on somebody. What you can do is have an environmental attack. If the day is exceptionally hot or exceptionally cold, have a +2 environmental hazard against which they have to roll every hour (if it is just
very bad weather), every ten minutes (if they're in a desert at midday or tundra at night) or every 1 minute at +3 (if they're in the Antarctic or close to a major forest fire).
Someone with no endurance skill would last a couple hours in the very bad weather, less than half an hour in the desert/tundra and less than 2 minutes in the Antarctic or near a major fire before he starts taking consequences.
Someone with good endurance would last 9 hours, one and a half hour and six minutes respectively.
Someone with superb endurance would last one week, a bit over a day and nearly three hours, respectively.
Then you can start adding modifiers in the way of roll-important aspects. Someone being naked could well help them against hot weather (+2) but severely hinder them if they're in the Antarctic (-2)
(and yes, the above numbers reflect reality pretty accurately. I checked the numbers-especially for underssed people in the Antarctic)
Similarly, you can apply
narrative-important aspects. If someone just shoots their guns a couple of times, no jamming. If someone has been in several prolonged firefights already and hasn't cleaned/worked on his gun, then jamming can happen. Not automatically; have it an an "environmental attack" against the gun's endurance. +0 vs what you decide is jamming endurance if it is clean, +1 if it was a couple of fights without being worked on, +2 if it has been several engagements without being worked on and so on. If the gun hasn't been cleaned for a decade (it might happen) then it might face a Legendary (+8) jamming "attack" when used.
Now, all guns do NOT have the same endurance.
An old-tech gun prone to jamming; mediocre endurance, 2 stress. A +2 jamming "attack" almost certainly will take it out and it may even jam right after cleaning in a really bad roll.
A modern gun prone to jamming; average endurance, 3 stress. +3 attacks typically jam it.
A modern quality automatic; average endurance, 3 stress.
A modern quality revolver; fair to good endurance, 4 stress. It needs serious neglect (or serious magic) to jam.
A modern military machinegun; good endurance, 4 stress. It needs serious neglect to jam but magic may hex it.
A very high quality handmade revolver of a simple but heavy, antijamming design made of tungsten and tantalium; Legandary Endurance, 5 stress. You could fire it if you had just unearthed it from a century-old tomb and only very powerful magic could hex it.