The Rune Pure has its name because it wears rune armor. To wear rune armor, you need have 40 defense. It uses the whip, dragon scimitar, dragon longsword, and the dds as its main choice of weapons. For richer pures, the whip and dds is used. For the poorer Rune Pures, you will want to use a dragon scimitar or dragon longsword with the dds. If you really don't have money to waste, but your levels are 70 attack + and 99 strength, you can try using just a dds to spec them out.
The Rune Pure, like I mentioned before, wears rune full armor, minus the kiteshield. In place of the kiteshield, you will want the rune defender, which can be obtained by going to the Warrior's Guild in Burthrope. Collect points by any of the ways possible in the entire guild and then head upstairs to kill Cyclopses to get defenders. You will have to work your way up from bronze to rune. Once you get rune, you might want to keep training on them and collect as many rune defenders as possible so you will not have to get these later, if you die.
You can wear a strength amulet, climbing boots, and rune gloves. To find out how to get climbing, take a look at "Runescape Pking Rs Guide (Part 4): The DDS Pure" and it will explain a brief summary how to get it. To get rune gloves, you need to complete more of "Recipie for Disaster", which you worked on for the mithril gloves.