Need something for work, needs to conceal under a suit and sometimes just a polo. Thinking buy once, cry once. Any recommendations?

Don't know that a IIIa vest will really conceal under a polo. Tried it once and it was really obvious I was wearing the vest.  They're pretty thick.

this? no experience with one but looks pretty slick

Not stab resistant.

OP, you could call up Safariland and ask them. Just looking at their site they don't have any ballistic/stab combo vests though but they may sell something through one of their subsidiary brands that meets your needs.

SafeGuard Clothing sells a couple vests with varying ballistic and stab/spike ratings, but they don't have anything that's NIJ certified (not necessarily bad) and I don't know anything about the company personally.

You sure you want stab proof? It means a metal mesh in the armor making it much more heavy, costly, thick, stiff, etc. Stab proof armor is NOT very concealable. Stabs with normal knives through soft armor are quite shallow and soft armor is slash proof, just limit stabs to about an inch or less with knives. Stab proof armor stands up to an ice pick stab with high force. Not something you are likely to face. I would prioritize thinness, comfort, and concealability in soft armor. I'd also not hold so tight to the 3a demand... level 2 will stop pretty much all the same threats and usually fail on backface deformation only. If you are serious about concealability it is a serious consideration.

Very well stated.

I'll +1 this as well.  Ever try to cut soft armor with a knife?  Extremely difficult. Piercing it with a knife tip is easier, but still a lot of resistance.

Stab vests are typically worn by corrections officers, who (hopefully) don't have to worry about firearms. Spike type piercing weapons are much more of a concern to them.

Not necessarily, and that's actually not very likely anymore. Most stab vests now use Kevlar Correctional, Twaron, Microflex, or similar stab resistant fabrics. Chain mail is out as far as I can tell.

Second maybe stepping down to level II for ballistic protection. You'll get a much more flexible, slightly thinner vest that will make concealability easier.

Against the spike threat... yes.

Against knife threats... no.

Those fiber-based solutions, e.g. Kevlar Correctional, are really only used for anti-spike purposes.  For anti-knife purposes, metals are still generally required.  This is because the knife poses two problems:  The perforation problem (tip), and the cutting/shearing problem (sharp edge).  Put simply, fiber solutions don't take well to being cut, so they don't perform adequately against knife threats.

Because the knife problem is the far harder problem, spike-rated armor designs outnumber knife-rated armor designs by about four to one on the NIJ list:  https://tims.justnet.org/Report/StabCPL

Also note that the Kevlar Correctional marketing brochure only mentions the spike threat, and doesn't mention knives at all.

Spike-rated armor is pretty useless on the streets.  If I were looking for stab-rated armor and had to pick between chainmail and Kevlar Correctional, give me the chainmail.

Huh. Guess that explains why I don't see a lot of stuff with chain mail in it. I mean seriously, I can't find an example of a vest that uses chain mail. Everything I know of uses fabric or polycarb for anti stab protection. Looking closer though it seems they're all meant for spike threats but they use some wishy washy language to make it sound like they encompass edged blade threats as well.

Some of the polycarbonate solutions are very thick, and those do okay -- but not great -- against knife threats.

The kevlar-only stuff performs dismally.  This Spike-3 rated panel from Safariland wouldn't pass the Knife-1 test.  You'd see a complete penetration, every single time.

In fairness, part of the problem is that the knives that the NIJ uses for testing are too damn good.  They don't really resemble real knives.  They're super small, with a large and perfectly straight tip, and they are very sharp-edged.  They truly represent a worst case scenario for armor.  They're nothing like the dull folders or re-purposed kitchen knives you're likely to encounter on the streets.

But knife threats are impossibly tough for textile armors in general, even when the knife isn't very sharp -- for even dull knives can cut strands of kevlar, and you'd be surprised at how forceful a 36J stab really is.  So most of the knife-rated panels -- especially the Knife-2 and Knife-3 rated panels -- look like they could have been used at the Battle of Wisby.  Chain mail, or "coats of plate."

Just curious, what sort of threats are thinking you may encounter? This an EDC sort of thing?

The last time I saw a Second Chance stab panel, it was a demo that had been shot at.  The difference appeared to be the tightness of the weave, that was it.
The stab panel was very thin compared to a standard ballistic panel, perhaps 1/4 of the thickness. It stopped large diameter calibers, but the small .22lr went through.

Just buy a normal vest. If you want thin, grab a IIa. If you want "duty", grab a II.

I wonder who makes These