You know what, I've worked it out. The inspect tool. I'll take it from here myself thanks Ziggy!
For anyone else reading, here's what I used in the end once I'd changed the blog style to masonry (seemed to lay things out more sensibly):
.blog-masonry .blog-title {
font-family: 'Waymar'
}
.blog-masonry .blog-date {
font-family: 'Open Sans';
font-size:1.4rem
}
.blog-item-wrapper .blog-item-title h1.entry-title {
font-family: 'Waymar';
}
.blog-item-wrapper .blog-meta-item, .blog-item-wrapper .blog-meta-item a, .blog-item-wrapper .blog-meta-item span {
font-family: 'Gistesy';
font-size:4rem
}
.item-pagination-link .item-pagination-title {
font-family: 'Waymar'
}