I have a half inch cordless impact driver, I use a 3/8 adapter with it occasionally.
Anyone know of Torque spec for the adapter to snap?

I’m just worried the adapter will snap
I believe drive adapters are the weak link. I try to avoid them. ....
I even bought the 3/8" drive impact sockets. Live and learn.
Snap-On has a nice one with a replaceable square drive.
I can only speak for myself. I use those odd adapters when I got **** all over the place and I can not for the life of me find the right size drive and I have to use whatever I can get my hands on.
placed on different ratchets and small cordless impacts and like you I grab what is handiest many times. Especially if I want 6 point. And I use mostly impact grade stuff now too
No, but I looked it up for you.You got a part number or link
Ran across this one on a shelf in the garage, not sure why I didn't toss it other than to aggravate myself each time I see it.
I do have an impact extension, about 4", that is 1/2" female be 3/8" male.

I remember SK having warnings of these adapters were not guaranteed at all.

Is there any reason to have a 1/2 to 3/8 adapter for a ratchet to socket ?
I remember SK having warnings of these adapters were not guaranteed at all.
Its not about the strength. Its about noodling a combination of stuff together to get an awkward nut/bolt in a tight space... using hand tools.
That's how they get used in my toolbox anyway.
I believe drive adapters are the weak link. I try to avoid them. My 1/2' drive sockets range from 3/8" to 1 1/4" so about the only time I use one is on my 1/2" drive Bosch cordless impact if I'm using 3/8" drive impact sockets. But I try to avoid that. In fact, I'm sorry
I even bought the 3/8" drive impact sockets. Live and learn.
My 3/8" drive sockets go through 1" and my 1/4" drive go through 5/8" so I'm pretty well set without using them. I'd be more concerned about using too small of a drive size than anything else.
I believe drive adapters are the weak link. I try to avoid them.