Her consciousness ending up inside Deus/Wave Existence (and pushing its remainders into orbit) towards the end of the game you might think scales her to 1-C, but not only were characters ******** their pants at potential planet busting in that same instance, she also has little in the way of physical feats outside of Vierge to actually justify this. Although the 'Sophia' side of her being a subconscious limiter for Id within Fei (who near the end of the 1st disc / start of the 2nd iirc was implied to be life wiper at his peak) could put her at around Moon Level / close to small planet (5-C - Low 5-B).
The OG PS1 Xenogears is also alarmingly lousy for speed tiers, with not a lot being stated for it despite being honest about power (City, Continent or Planet all being either heavily implied or just outright stated). Fei has one possibly infinite speed feat with chasing Deus/Elly into orbit before the Wave Existence gets involved, but this was Weltall-X (yes, I know his mech is called 'Xenogears' at the end of the game, but given that's the name of the game, that would just get way too confusing lol), the only one that could still function after the defeat of Deus shut down the Zohar Modifier, implying that Vierge (as well as the other Gears and even the 3 other obtained Omnigears by Billy/Bart/Rico) could not pull this off. Even still, this is if I'm even willing to justify giving characters their mechs, to which I'm not otherwise Asuna wouldn't even be a candidate for her opponent (although if you saw how Elly fights... yeah, Reki? I take it you played this game?). Take a look at Breakthrough and tell me if this looks familiar:
Now before you say that 'this sounds like a stomp' keep in mind that A) there are debates about continent / tier 6 Kirito going on as we speak (that Asuna likely scales to) and B) that if Asuna (or any SAO character, for that matter) comes to Death Battle, they may forgo the recent nerfs entirely and do their own thing (which could mean anything, inc. tier 4 Abyssal Horror depending on what they interpret that as (if it wasn't ill-defined enough already)). Not to mention the lack of defined speed tiers for the Xenogears cast that have most of them at... what, bullet timing? Supersonic? Idk.
Then I forgot to mention how both of these characters have gone through damsel in distress arcs.
But yeah, I'm glad you bought all that up, because I finished a trailer for this MU just now:
