The Legacy tooltip could be more clear - we'll look at improving it in the future. The perk itself (as noted earlier in the thread) does increase the chance of getting an augment slot on items that can have them. For items that can't, it gives you an increased chance for the effect of a critical when crafting those items (like producing an extra item).
AllisonBerryman, does it increase your companions chance to critical on resource missions? Or only on producing crafted items?