It depends on whether the observer is currently using AR or is not using any Matrix User Mode at all.
Anyone with a commlink and image link can see AROs, but that's not the same thing as being in AR. At least not in 6we, at least. (My understanding in 5e was that the trinay condition everyone was in at all times was "No Commlink/Commlink is shut off, AR, and VR. Whether I grokked that correctly or not for 5e, that's not how it is in 6we....)
So if the cop is just "hanging out" all normal like, he'll only see the guns and grenades if he passes a perception test as described in the concealing gear rules (pg 246). However, PC1 could still be broadcasting AROs that are evident to everyone nearby with a commlink and imagelink. So if a hacker makes PC1 broadcast a holographic red arrow that flashes "GUN HIDDEN HERE" the cop will still see that.
OTOH if the cop is actively using AR, a matrix perception test against his PAN is what's called for (see pg. 182-183). Now if the guns and grenades aren't running silent, there's no need to spot them. They're just automagically visible to anyone who bothers to perform a matrix perception check, although a matrix perception check still could get specific details at GM discretion, like how long the user has owned it, what specific make/model gun, etc.