You can also use thin superglue to fill some gaps, it flows and soaks better.
Many guards are fitted with JB Weld which is an excellent metal-metal adhesive. Solder comes in all sorts, any soldering has to be done before the handle is fitted, so you can't do it to a finished knife. You can however get it in both low and high temp types. Steve Johnson, a VERY well known US maker uses solder that melts at such a low temp that he uses just a hot air gun.
The Puukko doesn't have the SPT/PT induction hardened blade. Harder spine, softer edge than the Wolverine. The induction hardening method isn't in any way exclusive to, or developed by, Kellam and the Lauri blades appear indistiguishable to me.
I don't like the handle on the Wolverine, doesn't suit my hand, but Stuart and Ed swear by them and have worked them really hard.