If we're talking about PvP terms, Thief is a class centred on a <<Mega-f*cking tactic mind>> that could beat you without good Daggers in... 0,5 sec's.
Martial Artist is a good tank if we're talking about his Deffense Buff. And a good damager, too. But I see this class like a... slow-attacker guy compared to the evasive Thief. I'm 46/45, and normally I don't get hit.
MA IMO, should be in any party that has a lot of p-dps (although m-dps is more prevalent). This is due to suppress (100% crit dmg debuff). They gain insane amounts of attack and attack speed with charge and can take a hit when under defenders strength (I believe I hit 70% defense at lvl 70).
I would rank a geared MA near the top if not top p-dps class with its valuable Supress debuff and overall damage potential, especially when awakened dagger is on its off hand though awakened katana Samurai would probably outdamage MA at this point (though if we exclude awakened weapons, MA is probably naturally the better 1vs1 damage). I haven't done a side by side comparison yet but Im funding my couple to awaken the katana I gave her.
FYI, I use collapsing blow glyph which gives -20 physical resistance debuff when stacked. It's a bit confusing since I was under the impression you must be under attack for the effect to happen (similar to Thief's Heartless glyph) but it's not as it stacks while you attack with Collapsing Blow active on the mob. This is the better PvE gylph in my opinion for damage since there's no charge glyph. Im gonna try out a run with both my couple being a Sammy and myself as MA.
That's -40 physical resistance (20 from collapsing blow glyph 20 from protrusion), 100% p-crit dmg, -X defense and -10 elemental resistance (possible 20 if we both use heaven fire/fire soul ring between us which will give -20% defense as well) just between us.
The above is actually a pet peeve of mine. I dont understand why un-geared p-dps dont mix and match to fit their party's needs. Becoming a thief or Samurai (for the reasons above) would've been far more helpful, with thief's Ambush and samurai's debuffs.