Sorry wamm, but by the end of any of Samus' 2D games she might as well be some sort of demi-god.
Samus is very agile, very fast, and with the speed booster she can run at super sonic speeds, becomes nigh invincible, and crushes anything in her path.
Power Beam, Charge Beam, Wave Beam, Ice Beam, Plasma Beam, all combine to create a weapon of considerable power that can pierce through metal and flesh alike. Additionally the Hyper Beam is far beyond even all of that.
I'm confident that direct rocket strike from a Human rocket launcher of the Halo series would kill the Arbiter with a direct hit. Samus' technology being far above the humans of the Halo series it would only take one of her rockets to kill him. Samus' suit creates fully formed missles from only the energy created in her own suit, which is infinite. Also she can fire five homing missles at once at one target, or 5 different targets. That's more than enough to kill the Arbiter in one salvo.
Bombs, Power Bombs, Space jump, Screw attack... there is so MUCH more that Samus has, this is just a very small sample... Really... the Arbiter stands no chance.
Gender: Male Location: on Corvette, teabagging some Hunter
Spite. You shouldn't put the Arbiter, or any of the Halo characters, for that matter, against the major charaters (Ex. Akuma, Hero of Time Link, Samus, Kratos, Cloud or Seph, etc.). I'd say Arbiter is in the middle-class of characters (Ex. Wesker, Master Chief, etc.)
Gender: Male Location: 1/9.7'rd Horseman of the Apocalypse
MC is middle class because every major character listed, minus Cloud, can rip his arms off. Sephiroth would have to use TK, but he still technicly can.
Also, Mario can lift an entire castle over his head.