What's the best way to connect pieces of a large print after printing? I have a number of fairly large printed pieces.  The parts, when assembled, form a very large sword.  (The model is this: https://www.thingiverse.com/thing:4178060, and is not mine.)  It is about 7' from tip to pommel, and individual pieces are fairly large.  The pieces are already printed, so advice to modify the model geometry to add reinforcements at this point is moot.
I have printed the pieces in PLA.  I'm not asking for glue recommendations, necessarily, but rather something that could help with adhesion in addition to the glue. I'm concerned that after gluing them together, they won't support their own weight very well. I'm not worried about swinging it, just holding it and hanging it on a wall.
If I was very clever, I would have modified the files to add a through-hole that I would've put a pipe through or something, but I didn't think that far ahead.  I could drill holes in the printed pieces, but I don't have a good way to make sure they line up.
So, what is the best way to add some kind of support to help keep the parts from falling apart? Is there some trick I could use to figure out how to line up drill holes?
Previous answer assuming not yet printed:
If you want to drill holes, print smaller guide holes to guide the drill bit.  The best glue depends on the material.  Printing structures like dovetails makes the connection less dependent on the strength of the glue.
Answer with the parts already printed:
The best way to align drilled holes is probably to glue the pieces together first, then drill the holes.  Otherwise, you need a method to clamp the pieces together or do precision drilling.