If the article's URL is the slug, then the /1 shouldn't be mistaken as an article ID.
/blog/article-title -> is an article
/blog/2 -> is a page
From a UX point of view, /blog/page/2 does make more sense: if for example the URL is shared, the reader can better guess what is the content going to be. Even *if* putting more keywords in the URL is bad for SEO, the only keywords in this URL are going to be blog and the domain name, then there isn't much to loose if you add one keyword more.
In conlusion: /blog/page/X has a better usability that outbalances the possible SEO penalization of having (just) one more keyword.