Your mesh has some modeling issues :).
I'll talk only about your Pommel object here.
01) Lots of N-gons
N-gons (faces with more than 4 sides) don't work well with shading or Subdivision modifier.
It's better to use quads and tris.
You original mesh left, repaired right
02) Overlapping geometry
This is a big problem in 3D modelling.
You have double edges, vertices and faces.
Some can be cleaned up by Mesh->Clean up->Merge by distance, but others have to be cleaned manually.
03) Flipped normals
Normals show which way a polygon is facing. If they're not facing the same way, it causes problems with shading and Subdivision.
You can check your normals here.
Blue should be facing out, red should be facing in.
To fix all, select your whole mesh and go to Mesh->Normals->Recalculate outside.
Your origin point isn't in the center - it's a tiny bit to the side.
This causes problems with the Mirror modifier.
Other tips for your workflow:
Set your units to milimeters for better precision.
Use orthographic view - it will help you be more precise.
Enable absolute grid snap - it will snap precisely to your grid.
Mirror modifier has a Clipping option - use it.
You're doing great so far, don't feel discouraged.
Good luck with your model, you're on the right track :).
Here is the repaired file: