OK, as I am new here, I will defer to others advice, but i have been painting on a semi-pro level for many years. I even work for a painting company.
You can go two ways with weapons.... non-metal metalics... not just for professionals.... you just need ot be ablke to blend and paint straight lines.... and metalics.
The way I layer metalics is pretty simple.
1. I start with Iron Wind or Parth "Steel".. is is very dark.
2. I decide which side to highlight (usually the one that best shows off the weapon or armor angle).
3. I paint the leading edge or flat with a mix of Steel and GW Chainmail.
4. I crest just the edge with GW shining silver.
That will give a 3 fold shading effect. You can also hit the back side of the blade or reverse slope of the armor with a ligth drybrush of the silver.
Now, when I say reverse side or opposite edge, I mean the adjoining surfaces. Id the blade is flat, I will paint it steel and then take a black thin paint pen or fine brush and paint a straight line down the center to give it depth.
On armors, I will then usually follow all of the painting with an ink wash...depending upon the look I want to go for.... rusty, shiney, old, etc..... redbrown ink, clear seal or black respectively.
I hope this helps a little bit.
When you get copmfortabel with this, you can then start using a very fine brush... tripple 0 (use SABLE)..... and start painting on reflective lieght in the form of star shapes etc.... to highlight one specific area. The same you would do on a pommel gem.