That's certainly a decent enough size for a knife.
I guess you misunderstood me: I was not proposing that the pattern was "faked" by wax "artwork" and acid etching.
IMHO this kard isn't made from wootz steel (I reckon that this is what "joar" specifically refers to in the Near/Middle East, isn't it?). However, I am positive that this is a really nice pattern-welded blade: it obviously has several rows of twistcore (often referred to as "turkish ribbon" but I don't know the Arabic name for this pattern).
this knife it's not an item of "Cour" either for parade or display,
not luxurious at all
it looks much more a weapon for honest warrior, no more
Well, it certainly was also a piece of pride for his owners (judging from the decorated hilt, etc.). And since twistcore is a bit weaker than randomly pattern-welded steel and a lot of effort and skill is needed to craft such a "turkish ribbon" blade, I feel certain to assume that the pattern was meant to be visible/shown. I don't know which type of etching would have traditionally been done on pattern-welded blades in central Asia to reveal the pattern but would guess that they utilized the same routine as with wootz blades. However, for keeping the pattern visible the owner would hardly need more than continue utilizing the knife and cut a fruit once in a while...
I don't know wether you can find someone in Cairo who could give this blade an etch (and is knowlegdeable enough to trust with working on an antique blade). If not, I'm quite sure that you can do this yourself: Thoroughly clean the blade with hot water and a strong detergent (a hard toothbrush and toothpaste or kitchen cleaning powder/cream may help to get gunk out of crevices), wipe the still hot (and wet) blade with a lime fruit (or rather cut it several times to work both sides at once), rinse with plenty of water (I prefer hot diluted vinegar), flick fluid off the blade (when working outside) and wipe off remaining moisture with an well-oiled rag; thoroughly dry with a hair dryer. If the contrast is not strong enough when rinsing, try another cleaning and etching cycle or two...
Before starting the whole process it's advisable to protect the hilt as much as feasible - a bit of wax and some sticky tape usually does the job.