Weapon moving
Sometimes you may want to move weapons about to prepare for some situation or another - arranging spare weapons in a future battlefield perhaps. Here's some advice on doing this efficiently.
Basic method
You can effectively move a weapon from one place to another by repeatedly swapping as you run, each swap causing your held weapon to be thrown forwards. There's no need to pause at each swap; you can do it whilst running non-stop, even going around bends. Practice and you should soon get the hang of it.
Jump-swapping
There's a variant of this I call 'jump-swapping', which I discovered by accident one day. If you hit the jump button a fraction of a second after hitting the swap button, you jump as you swap, causing your held weapon to get thrown forwards much further than normal. It's sort of fun if you're getting bored with the usual way, and it also means you don't have to swap so often. The timing takes a bit of getting used to though, i.e. to hit the jump button not too early and not too late.
Jump-swapping can also be used to throw a weapon up onto a high surface, by doing it whilst looking up. For example it enables you to get extra weapons up on top of the Silent Cartographer island, as described in On top of the island.
Moving more than one at once
You can move more than one weapon at once. Imagine you've got a few lying ahead of you in a line. As you move forwards, swap each time you pass over a weapon, causing your thrown weapon to extend the line. Get the idea? It's like a bunch of things rolling around in a washing machine. Over long distances this technique is more efficient than moving one weapon to your destination then coming back to move the next and so on. You have to hit the swap button more often, but you do less running. I often use this when creating a save that features a weapons stash built up somewhere.
Blasting
If you've got a Banshee handy you can move weapons by blasting them along. That can make a nice change from having to keep pressing the swap button, and it's potentially faster too. It can also enable you to get weapons past enemies while remaining safe. Weapons can fly quite a way and it's actually sort of fun to propel them where you want, but you have to be careful not to lose track of them. I'd advise getting a checkpoint to consolidate your progress occasionally if possible, just in case anything goes wrong.
I've used this method in level 5 to move weapons from early areas to much later areas for use in megabattles or other situations, typically after throwing them off the first bridge. You can consolidate with a tunnel checkpoint whenever you like. However, once you've blasted your weapons across the loading point in the tunnel after the underground bridge, I recommend moving them on foot until they're over the last hump of the paved surface, else weapons may spontaneously vanish when blasted. I experienced that repeatedly when blasting them in the corner after the loading point.