So, I was just thinking about wand flexibility and how it seems kind of sad that Pottermore doesn't go in-depth about what the various flexibilities mean exactly (besides talking about adaptability and willingness to change). So... I just thought I'd try and make something up myself... Just some thoughts... and you guys can chime in with your thoughts and ideas/descriptions or what have you, too.
Surprisingly swishy- A wand with this flexibility will either surprise its owner by being surprisingly loyal or surprisingly unloyal and is most often known for doing the unexpected. It is usually great for charm work. Owners that are matched with wands of this flexibility are usually the type of people who have a hard time coming out of their shell or opening up, but once they do, others will find themselves drawn to their charming, fun-loving personalities. The owner usually adapts well to unexpected changes but may find it difficult to make hard decisions.
Swishy- A wand with this flexibility may not be too loyal to its owner and may switch loyalties at a moment's notice. It is particularly good at charms. Owners that are matched with wands of this flexibility may be very sociable and fun-loving with a penchant for some mischief-making. They are usually very clever and prefer not to tie themselves down to any particular way of thinking until they've gathered all that they need to know.
Slightly springy- A wand with this flexibility may not appear to be very loyal at all because they will initially take to new owners quite well, but the fact of the matter is that they will always have a special tie to their original owner. As time goes on, this wand will become increasingly more troublesome for any owner that isn't its original owner until finally it stops working altogether. This wand is good for crafting spells. Owners matched with this wand may be very cheerful and optimistic, but most of all, they have very big (and possibly overactive) imaginations. Their thought patterns tend to be outside of the box.
Fairly bendy- A wand with this flexibility tends to be very loyal to its original owner; if it finds itself in a new owner's hands, it will make itself difficult to work with, but with time, it will eventually warm up to a new owner. This wand is not exceptional at any particular branch of magic but is well-rounded enough that it will do well or average in every area. Owners of a fairly bendy wand are well-liked but pride themselves on trying to stand out from the crowd. Unfortunately, some of them may be quite susceptible to peer pressure, usually brought on by being in a group considered "different" from others.
Very flexible- A wand with this flexibility is happy in anyone's hands, but this disadvantage is somewhat off-set by the fact that this wand does exceptionally well in just about every area of magic. Owners of this wand flexibility come with a very wide variety of personalities, but they do share a very high level of adaptability to just about any situation and an easy-going nature.
Quite flexible- A wand with this flexibility will pose little to no difficulty to whoever possesses it with the exception of owners it considers restrictive and/or boring. It is particularly good for transfiguration, spell crafting, healing magic, and curses. The owner of this wand is usually very likable as a result of being diplomatic and able to see all sides of a situation. They may be very indecisive, but they do have a few principles on which they believe very strongly in.
Supple- A wand with this flexibility needs a little time before it will warm up to its owner, but once it does, it will become very loyal. Once it has become loyal to an owner, it will have difficulty performing for a new owner unless that owner has a particularly dominating or forceful personality. It is particularly good for healing magic and any magic needed for potions or domestic activities like cooking. Supple wand owners are usually gentle, warm, humble, and kind-hearted. They may need to be careful about not burning themselves out in an attempt to please everyone.
Reasonably supple- A wand with this flexibility will take even more time than a supple wand before warming up to its owner, but it also will become very loyal once it does. Unlike supple wands, however, it will have difficulty performing for any new owner unless they prove their worthiness. Reasonably supple wands are usually well-rounded and perform average or well in just about every area of magic except for curses and jinxes. Owners of wands with this flexibility are patient and kind, but they have limits to this patience and kindness. They are not as likely to burn themselves out in an attempt to please everyone, but it is still possible.
Pliant- A wand with this flexibility will warm up easily to just about anyone; although, its full potential will not be unlocked until its owner has reached his or her full potential as well. This wand's talents will depend solely upon the owner's own talents, and its weaknesses will depend solely upon its owner's weaknesses. Pliant wand owners are eager, enthusiastic, and tend to be very easily impressed and/or naive. They often have a zest for life that is rare and unrivaled in most populations.
Slightly yielding- A wand with this flexibility will initially resist new owners, but if the owner is persistent, it will warm up eventually. It is particularly good for spells involving potion-making, animal-taming, and defensive magic, although, it may have a little bit of difficulty with nonverbal magic. Wand owners with slightly yielding wands are often very kind and compassionate, but they may have some reluctance in trusting others since they possess a strong sense of skepticism. It usually takes a lot of strong arguing before the owner of this wand will believe claims that don't make any sense to them.
Brittle- A wand with this flexibility tends to attach itself quickest to owners who have insecurities, and its level of loyalty is often dependent on how loyal the owner is to it. Should it become very loyal to its original owner, new owners often won't get the chance to earn the wand's loyalty before it breaks. Brittle wands are best suited to subtle and delicate magic, such as transfiguration and non-verbal spell-casting. Because they break easy, their owners should be careful to avoid magic that is unnecessarily flashy or explosive, especially if the wand also has a dragon heartstring core. Owners with this wand flexibility are usually contemplative, clever, and somewhat cynical; they tend to be an "underdog" type of person and perhaps even a little bit unlucky, which could lead them to becoming resentful of their more successful peers. If a brittle wand owner perseveres and manages to get over their insecurities, however, he or she will often become a "great success story" that never ceases to amaze and inspire others.
Hard- A wand of this flexibility is very difficult to work with and its loyalty is not won easily. Hard wands are great for complex and advanced levels of magic, so beginning wizards and witches may find extra difficulty with this wand when it doesn't perform well for simple magic. As such, this type of wand is best suited for wizards and witches who are gifted, stubborn, and never give up. Owners of this wand also have a tendency to view things in absolutes; black or white. Some people may find them intimidating or difficult to approach.
Solid- A wand of this flexibility will become extremely loyal to one owner and one owner only, usually people of great moral integrity. It is a wand that usually heavily specializes in only one area of magic of its owner's choosing. Owners of this wand are generally known for their reliability, their friendliness, and their character. They may find it difficult to understand views that differ from their own but are usually able to politely disagree.
Rigid- A wand of this flexibility will only give its complete loyalty to an owner who has faced great personal tragedy. It is particularly good for practical magic use, and thus usually doesn't perform well for magic that is frivolous or silly. Rigid wand owners are cautious and have difficulty trusting others, but they are not usually unkind people. Generally, they prefer to be left alone so that they can do what they want to do, regardless of what anyone else says.
Unyielding- A wand of this flexibility finely tunes itself to its original owner's preferences and doesn't stray from those preferences, even in the hands of a new owner; the new owner will just have to get used to it. It is particularly good for combative and healing magic. Unyielding wand owners tend to be very confident in themselves and/or in the things they believe in. They tend to be intelligent, somewhat cynical, and usually have well-defined principles that they will not stray from ever. Sometimes, this combination can lead to arrogance because of them insisting on how right they are without considering other points of view or whether or not they might be wrong.
I think I might have missed a couple of flexibilities... if you don't see your wand's flexibility here... let me know, and I'll try to make up a description for it.