Well, as was said in the vats: let's try this again.
I forgot the smilie (again) in my first post. So it was not clear that my introductory sentence was meant to reflect amusement, not ranting in any way, form or shape. For that, I apologize. On Forums you can't read expressions, hear the tone of voice or body language so there's quite some room for misunderstandings or misinterpreting. My fault for adding a comment that could easily taken to be offensive without clarifying that this was not the intention.
The problem with armor mods in general is that there are such an awful lot of em. There are good ones and bad ones, technically speaking. There are lore friendly ones, there are a bit skimpy ones and skimpy ones and very, very skimpy ones. There are unbalanced ones and strange ones. For a lot of em there are replacer-versions and standalone versions. What matters in choosing them is taste. Tastes are different and since I do not know you or can read your mind I can't make recommendations.
I also do not know how much you know about modding in general or about modding-sites or about anything. It could be that you just installed the game and have a few hours game-experience and never searched for mods before. Directing you to the Nexus was a well intentioned suggestion, because it is the largest mod site out there for FO3 and FONV. The fact that there are tens of thousands of mods can be overwhelming, so making you aware of the tag search option sounded like a good idea. Apparently it was not.
If you had asked for a recommendation for a needs mod for example, then things would have gone way easier. Then I would have said that I would either use IMCN (complex, realistic) or Arwen (REALLY hardcore). With armor this is not possible. There are too many and tastes are too different. After having a look and try some of em you might then refine your search for your personal Topmod by asking stuff like: I used the t3m replacer and like the quality but the armors are a little too skimpy for my taste, what can you recommend me?
I will carefully refrain from recommending a bodyreplacer because obiously you don't do bodymods and don't see the need for one. So, in the event of you or someone else reading this installing an armor mod intended for some specific body without installing the necessary .nifs (let's see if you know what I mean) and then getting weird results, like boobs stretching off to infinity, strange ragdoll behaviour or such things I am sure someone else will gladly help you.
One of the often voiced complaints about bodyreplacers is that some people don't like nude bodies in the game. Well, I just pointed out that replacers, at least the good ones, come with variants, including clothed (undies) ones. So, in a completely non-sarcastic way I just wanted to make you aware of this.
Now for a sentence by sentence answer to your request so I do not get accused of not reading the post:
laclongquan said:
In Fallout New Vegas I'd like to change to appearance of female armors, specifically medium and heavy armor.
It would be very nice if the mod can just change the appearance of current existing armor like reinforced metal etc... I dont need added things because I fear breaking the fragile balance.
Choose a replacer. As mentioned, some armormods replace existing armor and some add new ones. The good mods offer a choice.
laclongquan said:
Failing that, can you recommend some medium/heavy armor mods?.
Not really, there are too many out there. T3m with the option of the t6 are good but require bodymods and so are out of the question. Besides it's on the nexus so you apparently do not want to go there.
laclongquan said:
Oh, and this is a must: They should feature some nekkid value, because otherwise what is the point, right?
The above mentioned mods have some nekkid value, so do others. But there are huge differences on how much skin they show, a bit, some, a lot , nearly all of it. Be more precise, get a more precise answer. Tastes are different.
laclongquan said:
EDIT: found a nice mod of Gecko metal, but it's vanilla, as in full body. Failed the final requirement, obviously. There's a Scrap Metal Armor mod, but I dont like it because it look slightly off. I will use it if I must but I'd like options.
the armor looks slightly off? That can mean a lot of things, amongst other meanings it could be that you do not use the correct t body for this mod.