There is a slight difference between someone who collects SpyderCo knives and someone who is registered and certified in the SpyderCo Collector Programs. It is these programs that the engraved number exists for and a numbered knife originates from said program. To registered collectors their number is gold.
In the SpyderCo Collector program, and there are several, a Collector receives a number. Thats his number until he is no longer in the program. I am #36. Based on my program I get first runs, production runs, variations, and sprints. That numbered run is ONLY available to thos registered members and we members are contractualy obligated to purchase our numbered knife as it is released. All the knives in my program have #36 engraved on them and each comes with a Cert of Auth with #36 and My name on it showing #36 is me. That number is only valid for me with that Cert. Any unnumbered variations of that run are made AFTER. That is guaranteed to me in writing and why I am in the program. Should I leave the program any #36 knives from a current run can and do become available to public sale. And #36 would then be open for another Collector to choose when he joined the program. You can email SpyderCo for a current list of available #'s if you are interested. Be aware that it is a commitment not to be taken lightly as you must purchase any and all numbered runs in your program and ee collectors have no say in what is released or produced.
In your case the number Guarantees authenticity and the knife's collectibility as a first run or variant. Is a #36 or #56 or #128 Damascus Blade Red Bone Endura worth more than an unnumbered one? Only if no unnumbered ones are available. Ha! To me yes, to someone else maybe not. If you don't have the certificate its the same as any other sprint run. And theres not much market for a cert with somebody else's name on it.