Making the mesh smooth
Our object is not smooth, it needs to be made smooth. Usually, this is done by Subdivision Surface modifier. But we need to do some tweaking while making our mesh smooth.
For our own convenience ,apply mirror modifiers on both objects.
Usually, users apply mirror modifiers when smoothing the mesh.
Join both objects by selecting them, and pressing Ctrl+J.
Now add Subdivision Surface modifier, by clicking Modifier properties > Add Modifier > Generate > Subdivision Surface.
Subdivision Surface converts faces of the mesh into smaller faces thus giving a smooth appearance, but this usually does not work for the sharp edges. Sharp edges need to be adjusted using Edge Loops.
Keep the Levels Viewport to 2.
Adding Loop Cuts
Select the sword, go to Edit Mode, and add Loop cuts using Loop Cuts tool or press Ctrl+R, make sure that the loop cut is near to the edge which you want to sharpen.
To make the rings more prominent, add loop cuts from multiple sides.
The image shown below is shown to have multiple loop cuts from each direction to make the ring more prominent.
As you can see, the cross guard of the sword can be adjusted by adding a loop cut along the z-axis.
Loop cuts need to be added on the sides of cross-guard.
Hiding surrounding vertices
Now, we will make the blade smooth. We will focus on the blade only and hide the grip.
Select the blade by hovering the mouse over the blade and press L key, this will select the blade.
Press H key, this will hide the blade, a menu will appear at the left bottom side, select Unselected, this will hide everything except the selected vertices.
We need to adjust the top of the blade, this can be done by selecting the top vertices and extruding using Extrude Region tool.
Make sure that extrude a little upwards, not too much.
Now, we are going to make the cavity sharper, to do that, we need to see the vertices of the cavity of fuller.
Disable Realtime display. This will show the original undivided mesh.
Similarly, Add Loop Cuts to make the mesh smooth.
Enable the Realtime Display.