I was sort of thinking of doing separate posts for different bladed tools, but honestly, I mainly use an Athame, and while I may have a few other bladed tools, they aren't primary for me, so I don't feel I would have enough to say on some of them. As a quick overview, I have two Athame (double-edged daggers), a white handled knife, a doctored up letter opener (not sharp by any definition) and a sword. These are my magical tools, my actual blade collection is quite a lot bigger. What can I say, I am a blade girl.
My Athame is my primary tool. If I am going to use just one tool, it will be my Athame. As I said, I have two, one is the very first one I ever bought for use and the other is my current one. But if I am going to start from the beginning, the very first blade I ever used in magic was a small pocket knife. It was a simple thing that I had been given by my Grandfather. It had just two blades, was slightly rusty and old. My Grandfather used to collect junk that other people threw away. He would walk the woods and come home with really crazy things, I loved it.
For a starter blade, the little pocket knife was perfect. Firstly it was small and easily concealed. I could carry it in my pocket, backpack or purse and really no one would notice or think about it if they did (it was actually quite a bit smaller and more dainty than my everyday pocket knife which was a huge serrated monstrosity). It was also a functional knife, so I could use it to carve or what not as needed as well as more purely magical operations.
At the time I was very big on tools and having read about the split in blades between the black and white handled knives, I set out to get my own. I found a lovely sushi knife at a kitchen store. It has a very pale (almost white, but not painted, just very pale) wooden handle and sheath. And it was fairly small (about a 4 inch blade or so) and quite sharp. For a working tool it was excellent. I especially appreciated that it came with it's own sheath so I didn't have to worry about accidentally cutting myself.
I was in Hawaii at the time, so wandering about one of the little swap meets, I found a selection of dive knives. They are not huge, small dagger size (about 4 inches as well). The ones I was looking at weren't the dive knives with the blunt end for prying things up but more traditionally daggery. They were double edged, with just about an inch by the hilt that was serrated (for cutting through cords if needed, but I have a preference for serrated blades, so it was wonderful for me). They were black handled, and they had one with a ying-yang symbol, which is one of the symbols I really am called to. They also came with a sheath, that had a belt loop on it. The one drawback was the handle and sheath were plastic, but I decided to try it anyways, and that blade became my Athame for close to ten years. I never had a problem with the plastic, in fact it was probably one of the things that led me to my disbelief in some of the non-modern thoughts on the magical use of things like plastic and technology.
Sometime around here I was looking for a more publicly usable blade. I knew that I couldn't go waving about these sharp blades, especially since I was still in school at the time. I had a letter opener that was very plain, just a silver looking blade shape, rounded on the edges and not very pointy. I managed to pretty it up a little with a grip (I don't even remember where I got it from, but it was black leather with little cut out patterns).
I didn't get my current Athame until about ten years or so ago. My husband and I were out at a swap meet, and I always look at blades when I see them. There was this little stall that had a couple of things, and one dagger caught my eye. It is longer than any that I had used before, from tip to tip it goes from my elbow to my fingertips. It was also heavier than I was used to. The blade was long, but thinner, much more spike like. The tip is quite pointy, even though the edges are still pretty dull. It can cut, but you have to use a lot of force to do so. The hilt guard and pommel are brass, a metal I don't really generally like, but most of the hilt grip is a kind of greenish-white bone, so it works well together. I went home with the dagger that day.
My sword was a valentines present from my husband (how well does he know me! I don't get chocolate and roses but blades *grin). It is on the smaller side, and slightly ornamental, and really only my dips into Ceremonial thought made me want a sword for magic at all, but I have one.
All of that and I still don't quite think I'm there yet on blade tools. I am too much a kitchen witch. I would like a dagger that has a good cutting edge that I could use, but haven't found one that calls to me yet.
Having said that though, I have a much deeper relationship with my Athame than any of my other tools. It is the only tool I have that has a name (which has never been told to anyone and probably never will). My Athame is a part of me, a companion in my workings and a personality on it's own (well most of my tools have personality, this one is just more pronounced to me).
So now that I've rambled about the tools I have, some thoughts on bladed tools in general.
I don't think that there is a hard and fast right/wrong for the blade you work with. I've worked with sharp, not-sharp, plastic, black/white/colored hilt. All the rules for magical blades I've broken at one time or another and never had a problem. What I think is important is what you want to do with your tool. If you like having just one tool to work with, then it will need to be more adaptable. If you don't mind having several, you can be more specialized and have a blade set aside for harvesting plants (some consider the Bioline to be only the curved sickle-like blade used for herb harvesting, some consider it to be the white-handled utility knife that does all the actual cutting).
One thing I will touch upon briefly is the belief that a ritual tool should be only for ritual. I definitely don't agree with this. I have no problem with people who choose to keep their ritual tools only for ritual, but I don't feel that using a tool for a non-ritual purpose in any way diminishes it's ritual power. Rather, I find that a closer association with a tool brings a tighter bond and more control in ritual. By correlation, I don't find anything wrong with using an Athame to actually cut stuff, it is a blade after all. If you want to have a separate tool for practical stuff, fine, but if you want to use one for all of it, that is fine too.
I have always worked with the blade as a tool of fire. I know that ceremonially, the sword/blade is air and the wand is fire, and some pagan groups use that association as well. I've seen some lovely explanations for why that is. But to me, the wand is wood (well mine are at least), and branches that have been surrounded by air, where the blade is metal and forged in fire. I also think that the wand is a less aggressive tool than the blade, so fire works better for the blade. It might also be an emotional pull, since I am drawn stronger to both the blade and fire than I am to air/wand.
So sitting here thinking about it, I really don't know why the handle is supposed to be black. My guess would be that the black holds all colors (well for pigment not light) or that it is meant to absorb any negativity, but I can't recall it ever being spelled out as to why it should be black (or double-edged for that matter). I do know that some covens require it, but if you are working on your own, I would go with whatever you like.
Speaking of which, the name Athame is one of those crazy touchy subjects that BTWs (British Traditional Wiccans) get proprietorial about. I've been flat out told that I can't use that word for my tool because it is not a proper consecrated-in-their-tradition tool and that is the only blade that is an actual Athame. There might be some truth to that, Gardener is often considered the originator of the term (even though a similar term was used for a black handled knife in the Key of Solomon). This is one of those places where I fill popular culture over-rides. I will never claim to have a consecrated BTW Athame (well unless I become a proper BTW and get one...but that is unlikely), however since the very first book I picked up, the working blade has been called an Athame, and that is what I call mine.