とする・にする before a noun


> 「 **竜の歯を依り代とした人型** はコルキス王の魔術と聞く。 その娘、王女メディアは稀代の魔女と謳われたそうだが？」

Does this mean:

> The human form who made the dragon tooth as a vessel

or

> A human form which was a dragon tooth made vessel.

How does にする・とする work before a name?




`A を B に／とする` means either _make A into B_ or _have A as B_. Whether the
change of state is involved or not (i.e. _A_ is "made" into _B_ or originally
so) is unspecified and always left ambiguous, so you can only choose the right
side from context.

> 人型 that made a dragon tooth into the (spirit) vessel  
>  _or_  
>  人型 using a dragon tooth as the (spirit) vessel

(I don't have any idea what 人型 stands for, though...)

This type of ambiguity is parallel to that of English passive construction.

> _The project is finally completed._ → changes from "WIP" to "done".  
>  _The project is already completed._ → keeps the "done" state.

If you dig a little deeper, using the particle に or と makes some difference in
nuance. According to [this
page](https://web.archive.org/web/20170910033102/http://www.alc.co.jp/jpn/article/faq/03/85.html),
と suggests the result is authentic, finalized, or established, whereas に
comparatively ad-hoc, questionable, or figurative.

There are some idioms exclusively allow either of them.

> ○
> [身を粉にする](http://dictionary.goo.ne.jp/edc/5000273001/meaning/m0u/%E8%BA%AB%E3%82%92%E7%B2%89%E3%81%AB%E3%81%99%E3%82%8B/)  
>  × 身を粉とする

