The problem here is, is it Black Maria using Armament Haki to punch Sanji using Armament Haki, or Black Maria just punching Sanji with her normal fist while he's using Armament Haki.
you know when a choice is arbitrary but someone uses their bias to pick one or the another... its annoying af and even more when no one calls out for it being ambivalent choice (that its can be one or another there aren't conditionally applicable) and not calling out the bias of who chooses one over the another..
you cannot know if one is using arnament (invisible) without themcalling it out ... so its a throw up and you honestly cannot say that they aren't because it wasn't mentioned coz we know sanji uses it frequently without calling it out .
the best resolution to this ambivalence is either assuming that the fighters who use haki are consistently using arnamnet in their fights util the call out for not using it or they aren't until they mention it , becasue claiming that one fighter is and the other isnt' is obviously a subjective take on the match .
this resolves many problems with sanji's experiences with vergo and doffy but now lets discuss some of maria.
Maria is someone who called out an all star for underestimating her greatly..so its very safe to assume that she knows haki especially in the NW but that doesn't mean she was using haki against sanji (who wasn't using haki from his words).. so if we assume that Maria wasn't using arnmanet but the fact that she stood up to someone higher in power for underestimating her... you should preemptively assume that her strength is formidable . But there is a problem with going this route is that its highly inconsistent and cannot be applied to other circumstance since we know Sanji is consistently using arnament without calling it out..luffy vs Doffy and sanji vs Doffy as well etc etc ... so choosing this route of haki users only calling out when using haki will provide discrepancies with haki in onepiece..
so its honestly very safe to assume that when 2 haki users are fighting eachother they use haki often... this will rid the bias aspect of claiming who uses haki and who wasn't and will surely be consistent and applicable to most if not every situation..
so its honestly safe to assume that Maria was using haki.. even if for the sake of the argument we assume she wasn't that still doesn't take away from her strength