Get a representation showing the the major and minor attributes of an item {Precision: 85, Power: 126, Ferocity: 85} -> [['Power'], ['Precision', 'Ferocity']]
function normalizeAttributes (attributes) {
  let mainAttributes = []
  let maxValue

  for (let key in attributes) {
    if (validAttributes.indexOf(key) === -1) {
      continue
    }

    if (!maxValue || attributes[key] > maxValue) {
      maxValue = attributes[key]
      mainAttributes = [key]
    } else if (attributes[key] === maxValue) {
      mainAttributes.push(key)
    }
  }

  let secondaryAttributes = Object.keys(attributes).filter(a =>
    mainAttributes.indexOf(a) === -1 &&
    validAttributes.indexOf(a) !== -1
  )
  return [mainAttributes, secondaryAttributes]
}