I'm not a swordsmith expert, so maybe someone else can chime in on his level of expertise, but the "non-traditional" blades were made a number of differing ways. It could have been made using traditional methods (hand-hammering, folding, etc) but with non-Japanese metal, or some smiths used hydraulic hammers. They still made great weapons and usually had a great look.
Most "non traditional" seki stamped blades are oil quenched. Oil quenching blades creates less forging flaws. Traditional water quenched blades takes much more skill to master. I've seen some excellent non traditional blades I wish were water quenched....
It's a traditional style tsuba, probably Edo period. You see a lot of them on Shin-Gunto. As to why,... a bit of individuality, iron/steel more practical than brass, or a cheap substitute for an expensive brass item..... Or even a nod to the Samurai tradition. I see a lot of them online, but not so many on the dealers tables.
Again it is a standard decorative technique, and symbol. It represents a centipede which is sacred to the god of war, Google "Mukade Tsuba" for more information. It's a nice Tsuba, I wish I had one like it.
Thinking further, I have only ever seen the old iron tsuba with "field mounts", the wooden saya with a leather cover.
It was bought as a bare blade, and then I had the stunning good luck to get a set of mounts that fit perfectly. These mounts arrived with a non standard and slightly dubious Tsuba. I rather envy (in a good way) the very nice piece that you have shared here, all complete and as carried when in use.