A couple of the girls here (13 or 14 years old) have forged a knife blade each out of some steel strip. They are as rough as you can imagine (the knives not the girls) but they are ferociously proud of what they have done. So next I want to get them to put wooden handles on them. Does anybody have any advice, please, on how this can be done with absolutely minimal tooling and very few resources. The local labourers recently chopped down some hardwood trees so I am planning on making the handles out of some of that material but really have no idea how or how, then, to anchor the handles to the knives.

One method is a tapered tang driven into a hole drilled partway into the handle from one end. If necessary you can forge a drill bit type point on the end of a metal rod and use that to drill the hole in the handle.

use a nail if no other material is available. Drill hole through both scales and the tang inset nail then dill for second nail. Take scales off heat treat then put nails back through the above and peen nail ends to hold it all together.

Is the tang, a hidden tang or a full tang? That way we know which type of handle you are looking to put on.

Full tang but it could be reduced if that is easier.

With minimal tools as your criteria,
--- your choices with full rectangular tang are to use nails or short pieces of soft iron, brass or copper to rivet them on, or to glue the two slab pieces on
--- you choices with hidden tapered tang is to friction fit and/or glue
--- your choices with full-length long thin tang is to thread and screw on an end nut, or to rivet on an end nut by hammering/fullering the end of the tang over the nut.

Full tang but it could be reduced if that is easier.

Let the wood dry or it will shrink and crack after you get the scales mounted.

A full length tang that is in the shape of the handle desired.

2 slabs of wood roughly 2 - 2 1/4" wide and about 3/8" thick. Length will be just a little longer than handle. One trick also is to cut the excess material down near to the handle. It will be less you have to sand. Drill 2, 1/8" holes in handle. I would use a torch to temper the tang to a bluebird blue in order to get it soft for drilling. Make sure the pins, whether brass or steel fit the holes. You might need to sand them down a little or widen the holes.

After holes are drilled in tang, put handle material on one side and clamp. Drill the hole through the handle material using the holes in the tang as placement guides. Do the same to the opposite side.

Add adhesive to the tang. Then place the handle material on one side, run the pins through the tang and place handle material on the other side running the pins through it also. Clamp and let set up.

After it has set up, you will be able to shape the handle.