Well, do you have a picture?
I have built 20-30 fishing rods, albiet fly rods. Most can be repaired if broken or something, though it looses a slight bit of action where repaired.
If the rod is in good shape, a couple small pieces of a broken rod can be inserted in the core, then epoxied and wraped. On some rods, you will see the tip open. If it is about 1/32 or more, just insert a piece of broken graphite rod with epoxy. This will reinforce the tippet. For the tip, a larger braid, from the, now old, braided butt leaders(maybe 60# or 100#, can be gently opened with a sharp pencil. After pushing it over the tip, you will find it frays quite a bit. A drop of super glue will mount it. Keep the glue about 1/8" below the tip/line mount! If you get epoxy or super glue in this area, it will get brittle and could snap. The tip and braid should just freely slide to allow good casting. Then carefully, shave the frays off with a razor: push away from the rod. 4-5 wraps of good silk will complete the process of attaching it. After mounting the on the end, epoxy over it to smooth out the finish. I use 5 minute epoxy, heat will later soften it to allow removal. The super glue can be removed/softened with toluene/acetone. Often remaining super glue can be sanded mostly clean. In about 15 minutes, you should be good to go.
The graphite from the pencil will lubricate the tip/line junction. A small extra fine piece of sand paper should be used to round this piece, providing more of a socket for the braided line to flex against.
Rather than using knots, I do the same with the line.
Strip the coating off a 1/4" of the base line. (I much prefer a tapered fly line, because they are generally easier to cast.) Then coat the braided part with super glue to stiffen it slightly. Insert this into the rod lilian braid. Super glue this in too. Then carefully wrap the joint with some flourescent thread, generally contrasting with your line color. Coat with a small amount of 5 minute epoxy.
I was using a loop to loop connector, but this was a little bulkey and I could "feel" it on the rod. The braided core line/glued connection is perfect for making the transition between the rod and line smoothly, and, keeps the braid from fraying. I have caught many 12-16 pound steelhead with the identical connection, soo, it is more than strong enough for smaller tenkara fish. I tested a few of these with a 25# weight with no breakage. I used to make braided butt leaders for a few fly shops in around Beaverkill, the Salmon River in Pulaski NY, and shops near the West Canada area in NY (also thousands of trout and steelhead flies to several Orvis shops around central NY.)