environmental weapon skills - how to use them

Warriors and eles each have 5 skills that allow them to place an environmental weapon on the ground - banners and conjure weapons. Whilst these are very popular and almost all dungeon teams do make use of them, it's very common to see people not using the right skills, picking the weapons up at the wrong time, or leaving them on the ground to waste. So here's some instructions on how I personally would like to see them used - not necessarily the most effective use, but almost certainly better than the random improvisation we seem to do at the moment.

Banner of Discipline - Unless you have a party full of warriors spamming "For Great Justice!", you probably don't have perma Fury. So pick the banner up, use Furious Rally (skill 2), and put it back down again.
Warbanner (AKA Battle Standard) - Mostly you should just leave this one on the ground, but occasionally it's appropriate to pick it up, use Whirlwind Banner (skill 2) for AoE stability, and put it back down again.
any banner - All banners have the same skills 3/4/5. Inspire (skill 3) grants swiftness so it's obviously great for running as a group, Sprint (skill 4) is a good gap closer, and Plant Standard (skill 5) provides a blast finisher while putting the banner down.
For all of those skills that grant boons, especially consider taking the time to use them if you have a considerable boost to boon duration.

The main reason to pick up a conjure weapon is to do more damage than your real weapon would, so ideally the person to pick it up will make the most of this with high power, crit chance, and crit damage. Don't bother if you're a greatsword warrior though; you're typically not gonna out-DPS your 100B. Let a mesmer or ranger or someone else with a weak weapon pick it up.
Conjure Fiery Greatsword - FGS is incredibly effective when your enemies are backed up against a wall or corner. Sometimes that's impossible (enemies fixed in place, no walls available etc etc), in which case the best you can do is auto attack or use Firestorm (skill 5) for AoE. But..! If the enemy is next to a wall, you can do insane amounts of damage. Point yourself directly at the wall, make sure you have nothing targeted (turn off auto-targeting koz it ruins everything) and use Fiery Rush (skill 4). If you do it right, you should mash your face into the wall, running on the spot and dropping fire at your feet. Every 0.1 seconds, you should do approximately 1 billion damage, and since you're not moving away from the enemy, all of those billions will hit, adding up to several billion. You can also use Fiery Whirl (skill 3) to do good damage whilst evading - it's just like Whirlwind Attack (on a warrior's so-called "greatsword", made of metal) but with a cooler animation.
Conjure Frost Bow - Usually if an ele just put this down, it means there's a static target with a large hit box e.g. the graveling burrows from AC, the Nightmare Tree from TA or the Eternal Flame from CoF path 2. Use Ice Storm (skill 4) so that entire AoE hits the target for superbig damage. The other skills can be situationally useful but they're not amazing. Read the descriptions and judge for yourself whether to use them or just drop the bow. Never bother auto-attacking with this because it's very very weak.
Conjure Lightning Hammer - Mostly when you see one of these go down, it's the main component of that ele's build. That means you need to consider carefully whether or not you should pick it up. It has a 60s cooldown, and only lasts about 30s if you keep attacking with it, so the ele is probably going to want to pick up the other one when their own runs out. However, sometimes you can be fairly sure that the ele won't be needing it, so you might as well help yourself to the spare hammer. This is okay when the fight won't last 30s and there'll be enough time afterwards for the cooldown, the ele has died, you know they have a FGS available, or they actually called out "lightning hammer!" for you to pick it up.
Assuming you have a lightning hammer in your hands, you should mostly just auto-attack with it. Lightning Leap (skill 2) is a gap closer with the added value of being a leap finisher, Wind Blast (skill 3) is a nice knockback, and Static Field (skill 5) can be good for stunning foes that run up to you, but those are all situational, and you can't go wrong with just smacking stuff - the auto-attack really is very powerful.