Have you been using Tumblr before? Because they made up a whole lot of meaningless terms that confuse people and have no meaning outside tumblr.
h1 is a tag that lets search engines know what is important. hr is a horizontal line with an attached div with some styled text next to the horizontal line. You like the way that text looks. So why not take the styling information used in the hr and add it to the h1 tag styling information. Putting a horizontal line inside h1 could be done as well.
I think you are confusing title as in <title></title> and h1 title (which you are using to describe a header of a section as a title of a section of text... i think you are misunderstanding something here the way you are using the words header title/ h1 tag ... wet water, dry desert ... all h1 tags by their definition are titles of sections (headers) within the content independent of page title html tags <title>Page Title</title>)
HR title has no meaning outside how it is used within the theme to describe text attached to a horizontal line with css. To a search engine it has no relevance unless the attached text is inside the h1-h6 tags.
I dont know if that makes sense to you but if it doesn't I suggest you read an html guide to get a better understanding.