Removed the required "Administer blocks" permission from everything except the "Custom block library" views page.
On the "Add custom block" page, restricted list based on "Create" permissions so there is less confusion.
On the "Custom block library" page, removed the "Block Description" column edit links so they appear as plain text. The edit links were always present even if the user didn't have edit permissions which could cause confusion. The "Operations" column edit links should be used instead which are permission based.