Fire is one of my worst elements, so I won't comment much on Vahagn, but, she's fast, strong and has debuffs, so, should easily find a spot on any team?
Intercept won't do anything if someone else has guard active, since the guarding hime will take the hit instead of Shamash... If you have light Athena or Attar or something, activate her guard when Shamash's intercept is on CD. In any case, Shamash starts losing her usefulness around mid-game 'cos intercept only works on normal attacks, and many rags/guards don't even do many if any normal attacks. She can still be good for orb control - her burst has orb eat, so you can make a boss OD much less frequently if you have a short burst cycle.
These aren't highly coveted but have their uses if you play as raid support (LB0 is good enough for these):
- Joan's lance if you use her
- Andro's staff is good for raid healers
- Andro's lance is good for extreme turtle builds
Remember that you need a MLB soul weapon for T4 souls, so any T4 souls you want, their respective T3 soul weapon will be game-changing/highly coveted i guess.