Lightweight backpacking requires individuals to think out-of-the-box and break from traditions likely taught for generations. For example, many "traditional" backpackers often carry emergency kits which may consist of an emergency tube tent or emergency blanket in addition to other items. I too would love to have an emergency shelter or blanket if put in a survival situation with no other gear. But these items are more for people who are in an emergency situation without gear, not for those carrying a pack full of stuff already. In my opinion, quite a bit of what traditional backpackers carry with them are very redundant and arguably unnecessary. Part of going "lightweight" requires the exercise of common sense, which sadly, is a fad that went out of our landscape long ago. It means giving up redundant gear, not because it couldn't help in a bad situation, but because it is often terribly unnecessary even in an emergency.
For me, there are many backpacking items I often think about quite deeply. I think moving towards a mini Swiss Army Classic knife likely was the something that required the most angst, and quite honestly, I'd still love to have a more robust knife with me because there is a side of me always thinking I'll be pressed into a serious survival or emergency situation despite the fact that my current gear would likely serve me just fine. Before going lightweight, I had carried a beautiful SOG knife which I still love despite the fact that it sits in my knife box along with several others which have become obsolete over the years. Oddly enough, I rarely use the mini knife I do carry and actually use the toothpick and scissor function more than the knife part.
My change to a lightweight knife was one of many choices I needed to make which I thought was a practical move. Yet, some lightweight backpackers take a far more hardline than I do, quite literally bringing only the big three with them (shelter, sleep system, pack) and often that's it with few exceptions (cooking systems are a pot over an open fire, rain gear is often unnecessary in the summer, a healthy yell can replace a whistle, skilled folks can start a fire without matches, etc.). But this style doesn't sit well with my sensibilities and I think it is important for each lightweight backpacker to make decisions based on their own skills, gear, and relevant to the environments they will encounter.
For example, one of the things I carry that I rarely see on any lightweight backpackers gear list is a very small mirror. Over the years, I have found it invaluable. It's great to look at for ticks on my backside, it's great to help pick a gnat out of my eye, it helps identify the seriousness of any wounds to my face (bee stings, fallen branches, etc.), and probably of greatest importance to me, it works as a signal mirror which is tremendously tough to duplicate in the backcountry. As a solo backpacker, I often can't rely on someone else to help with many of the functions that this mirror handles.
My personal thought about going "lightweight" is that it does NOT involve dumping every potentially useful item from your pack. Instead, it focuses on finding lighter and smaller solutions which are more reasonable and accomplish the same goal while otherwise cutting out redundant gear. So for me, the mirror remains in my pack, albeit small and light, but it remains.
One item that I've thought a lot about recently was cordage because it can offer so many dymanic uses. The only cordage I carry is that which I use for my bear bag. It is 50' of URSA Aircord Pro dyneema which can hold up to an absurd 1,400 pounds! It's light and strong...and completely overkill. I purchased it when I didn't want to bring along the heavier 550 paracord and probably should switch it out for something even more practical (and light).
My problem with the 550 paracord is the weight and the fact that it is susceptible to water retention (the dyneema cord is coated with urethane). Yet oddly enough, I think it is more useful overall. Being able to cut it open and have access to several strands of thinner cord is invaluable in a legitimate survival situation for snares, lashing, fishing line, bow, guylines, medical brace, and numerous other things which is one of the reasons I really want to carry it...yet I just can't make the mental leap to put it in my pack. Sure you could make cordage out of of braided saplings, vines, reeds, and all kinds of things nature provides...but the time and energy it would take to make something like that and the likelihood for it to be immediately functional isn't something I'll willing to roll the dice on when faced with a real survival situation.
Well, a handful of survival merchandisers have taken an old idea and made it mainstream. They have fashioned 550 paracord into belts and bracelets which can be unraveled as needed in a pinch. Bracelets offer around 24' of cord and belts around 125'. In fact, many manufacturers will actually give you a new one for free if you ever need it in an emergency, a marketing ploy that would require you to tell them your story so they could entice other potential buyers which your periling ordeal. Having this as a dual-use item, especially one not actually carried "in" the pack, may be a solution for a lightweight backpacker especially if it replaces a piece of gear you're going to be carrying anyway without any appreciable downside.
My point is that if you're someone like me who refuses to carry something like 550 paracord in your pack because of one reason or another....but you still want to figure out a way to have the flexibility it offers, perhaps you could use something like a 550 paracord belt or bracelet as a dual use item to justify it. That's not to say I'll be on the cutting edge of paracord fashion in the wilderness this season, but I am putting it in the "maybe" pile.
If you'd like to take a look, go to http://www.survivalstraps.com/ or take a look at much less expensive options on eBay. Course, this might be an item worth making yourself (http://www.wonderhowto.com/how-to-make-bracelet-with-550-paracord-362761/. You can purchase 1000' of cord for around $35 if you really look for it and the buckles are less than $1 each. While you're at it, make me one too...