Imperial armoury Warhammer 8th edition empire army book
The imperial armoury represents mainly the endeavours of the imperial engineers school and the variety of ranged black powder weapons (many still experimental) that they have invented. A couple of other things make it into the imperial armoury list namely the mechanical steed and full plate armour.
In the 7th edition empire army book most of these items came under the title of experimental weaponary and all remain in 8th edition though with some slight changes to stats and the addition of full plate mail to the list. A couple of them have had the slow to fire rule added which means they can no longer be used to stand and shoot, some ranges have also been increased.
Available only to the master engineer the only advantage of this mount over a flesh and blood one is that it inflicts impact hits on the charge and has a higher strength (though for a lower weapon skill and initiative). It also has a chance to lose part of its movement every turn and is now slower then in 7th edition it also no longer counts as a barded steed (though it can be bought slowing the mechanical steed down even further).
A master engineer mounted thus can be used to help keep small units of scouts or fast cavalry off of your war machines and gives him a chance to beat smaller units. This mount is generally more themed (and a fairly cool model) though it can occasionally be useful.
Fulll plate armour
Of the items that make up the imperial armoury full plate mail is the only one that is not manufactured by the imperial engineers school. Full plate mail is dwarf crafted and grants a better armour save then even heavy armour. Full plate mail grants the wearer a 4+ save that can be combined with shield, steed and barding and other items as normal. The empire actually seems to have a lot of full plate mail (more then the dwarfs themselves it would seem) as all greatswords and knights of every variety are clad in it. It is also an option for generals and captains of the empire to take. Full plate mail gives the knights of the empire their renown 1+ save making them almost impervious to low strength attacks, however they are vulnerable to any attack that bypasses armour saves.
Grenade launching blunderbuss
The grenade launching blunderbuss has had its range increased by 2" to a 18" it also now has the slow to fire rule meaning it can no longer be used to stand and shoot. Available to both master engineers and outrider's sharpshooters it can be useful to knock a wound off a large tough monster or to take out a heavily armoured knight, though as it is move or fire you will only get 2 or 3 shots off at best.
Hochland long rifle
The Hochland long rifle is the warhammer worlds equivalent of a sniper rifle allowing the user to single out specific targets even if hidden in units. Its best use seems to be to pick off unit champions (so preventing them challenging useful with Van Horstmann's speculum) or to wound enemy wizards (as then a miscast may just finish them off).
Remaining largely unchanged the only addition is the slow to fire rule preventing it being used to stand and shoot. the scientific precision rule has also now be replaced by the sniper rule which is effectively the same. There has also been a slight change in who can take a Hochland long rifle both hand gunners marksmen and engineers can still take one but outrider sharpshooters no longer can. However to compensate for this steam tank commanders can swap their repeating pistols for one.
The master engineer is the only character who can take these and they can be used to good effect especially against toughness 3 armies. The main change to pigeon bombs from 7th to 8th edition is the addition of a maximum range of 24" (rather then unlimited as it was in 7th). Using pigeon bombs is not without risk however there is a chance it will explode on the engineers head hitting those also nearby. Pigeon bombs use a chart to determine if they are on target or not and inflict a strength 4 armour piercing hit to anyone under the small template (including the engineer and friends on a bad roll) when they work well pigeon bombs can be quite deadly to large units.
Outriders are a special choice unit that are armed with these they are also available to master engineers and hand gunner marksmen. They give the model with it 3 strength 4 armour piercing shots though like hand guns these are also move or fire weapons. They can be a little expensive for hand gunner marksmen as for a similar cost you can buy 3 hand gunners who do the same have more wounds though of course take up more room.
It is in the hands of the outriders that these really shine as a fast cavalry unit they can use their pre game move to get into excellent firing positions and can pump out a lot of shots for a small unit. They can take some getting used to though as the move or fire special rule makes good postioning important.
Similar to the repeating handgun the repeater pistol gives the bearer 3 strength 4 shots (4 shots if combined with a normal pistol) that are armour piercing. All pistols have had the range increased to 12" in 8th edition and repeater pistols also have this range. Repeater pistols are also quick to fire so always allowing you to stand and shoot. Repeater pistols can also be used as additional hand weapons in melee combat.
Repeater pistols are available to master engineers (and do not use the additional pistol for 4 shots) they are also available in a brace consisting of pistol and repeater pistol for pistolier's outrider champions and outrider's sharpshooter champions. It is a good defensive weapon as you can always stand and shoot and also gives you an extra attack, it is worth noting it reduces the range of your outrider's sharp shooters ranged attacks which can be a problem.