I think it is just the direct translation of the word...maybe(?)

literally

similar, but more simple.

Size, scale, span sound good. But I'll prefer to focus on "restreint". So I'll say "limited proportions" for we have both the idea of "developpement" and "size".

'minhirs', except that the latter seem to be much more limited in their sophistication" [or, perhaps, "less developed" ?]

Say, what's the rush, MSH ?

I rather like Marie-Ange's "limited" for "restreint", though I'm not at all sure that "proportions" is what is meant by "development" here.

And Francis' "size/scale" *might* be what's intended, depending upon the context --but I think that it's quite possible that something less literal is meant, and "development" should be taken to mean something like the degree of "stylistic development" to be seen in these two different sets of artifacts : i.e., the "scepters" are more "developed" than the "objects" [=? spirals??] found on the [presumably earlier] minhirs.

That's my take on the meaning ; hard to say, without seeing pictures of what is being talked about.