Keltham taking off his jacket-shirt is going to look strange, to an inhabitant of Golarion not accustomed to overengineered dath ilani clothing.

In principle, one spends a lot of time in clothes, and hence should be willing to spend some money on better clothes.

In practice there is a certain element, in Civilization's clothing choices, of that dath ilani personality trait which always puts a hidden passageway behind at least one bookcase in the house library.  Often one that just goes around a short corner and exits from a different bookcase in the same library.  The point is, the hidden passageway has to be there, and if you ask why, the people of dath ilan will smile and tell you to shut up.

Keltham's jacket-shirt assembly includes more technology than just zipper slides.  It has been painstakingly designed by a cultural accumulation-over-time of engineers with +4sd intelligence to, among other things: manifest a rainproof hood from no obvious receptable, convert between warmer and colder coverage... and be easy to remove from yourself while you're already cuddling somebody, without having to disentangle yourself.  This easy-removal feature makes good use of micro-velcro fine enough to not be obvious from a distance, and arrays of tiny rare-earth magnets which automatically pull bits of fabric back together again in a correct stepwise pattern.

From an outside perspective, one would see Keltham tear his jacket-shirt off of himself with an audible ripping sound, and end up holding a jacket with no visible damage.  If you were watching closely enough, you'd see the jacket split along the seams and then quickly come together again along those same seams.  The way this registers from outside is not an accident or any kind of side effect of other design purposes.  A mad engineer who would detect in Golarion as INT 26 spent several years figuring out exactly how to do that and make it look cool, subsequently collecting 0.1-unskilled-labor-hour royalties on over 200,000,000 pieces of clothing.