BruceTheBatman said:
That lightsaber doesn't ignore durability since it struggles to cut through regular mooks and took time to cut Death Gun in half. And it was also resisted by DG's rapier-type sword that way logically comparable to Kirito's SAO weapons
There was no mention of Kirito's lightsaber taking time to cut something. If anything, it cut through pretty much anything Kirito hit immediately. The only thing that stopped it was Death Gun's estoc which is starship-grade metal, which is not remotely comparable to a metal sword or a crystal dragon excrement sword from SAO.
QUOTES:
Just when I stepped out at a speed as if I wanted to break through the virtual ground, I lunged forward without wasting any of the speed at all. In the world of SAO, it's called a «Vorpal Strike» a critical hit as it lunged into the enemy's chest.
The jet engine-like buzzing rang as the blade of light pierced through the enemy's body easily. It felt that the burst of energy that couldn't be vented anywhere else imploded inside the enemy. (Vol.5 Ch.6)
+ + +
The jet engine-like sound effect of metal even reached Sinon's ears while she was on the hill. The sharp end that had a
sure-kill ability was sucked in by the mantle.
...
The power of Kirito's one-handed thrust merely
left a burnt smell in the air and went by Death Gun. (Vol.6 Ch.14)
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Only a part of Death Gun's Estoc was burned, and there was no other damage. It could actually block the energy blade that had overwhelming power. Why—why is there such a thing?
...
"…Ku, ku. This guy's, material, is the, highest grade, metal, that could be, obtained, in, this game. I heard, that, it's a
galactic, warship, armor plate. Ku ku, ku…" (Vol.6 Ch.14)
+ + +
The energy blade sliced deep into Death Gun's right shoulder and then sliced in diagonally before leaving from his left abdomen. At this moment, the «black handgun» that was in his gun pouch was sliced in half by the lightsaber, and after giving off a bright orange flash, it exploded. (Vol.6 Ch.14)
+ + +
Anyways, Deathstrokes staff can surely one-shot Kirito, lightsaber or no. The only thing I can see Kirito can exploit is that it looks like the staff shoots like a gun and that the staff itself has no durability feats I can see (or at least, one that is comparable to metals used for building space warships). If anyone can shed light on that, I'd like to thank you in advance.
This would mean that Kirito can dodge the staff laser and would most probably be able to cut it. Any other weapon he has sans Godkiller (which would make it a stomp so ignore it) is Small Building level.
Anyway, weaponry analysis aside, Deathstroke has the tactical and experience advantage while Kirito has the variety and the higher AP (sans staff).
Going by in-character way of fighting, Deathstroke is likely to test the waters by shooting guns from afar, which Kirito will weave through. DS I think, would likely answer with going sword combat as well, which, going by DS' profile is not going to be in his favor due to the large strength gap.
Then there's Excalibur, which going by the interview with Kawahara Reki, raises his stats enough to overcome Yuuki's reflexes, Kirito's elemental sword skills and Starburst Stream which amps his already high attack to the point of killing off a boss with 3/4 health in 16 hits when his regular attack was only doing noticable but minute damage.
Anyways, Kirito for now 5.5/10 if only for variety.