Hints for Homebrew: Weaponry
Although clever and characterful unit design is important when writing up your custom army, just as important is the weapons cache you're going to send them into battle with. This is obviously a lot easier when designing a C3 or new Guard regiment, as you have a solid base to work from, adding only a few unique things that are often only trinkets for characters or new units. A new race on the other hand demands you to build up the entire weapon list. I'll cover hints for both these scenarios in this post.
Adding to an existing weapons portfolio
1) X Pattern: The obvious way to add a small distinction to your new Chapter or suchlike is to have some units have a different make of a standard weapon. Ideally this modification will help the unit perform their role within the army or allow them to do something that their parent unit couldn't do before.
Example: Sanguinary Guard. It would obviously be a bit naff to carry a normal bolter if you're a blingy assault unit, on account of it being Rapid Fire, so we get the Angelus pattern. This also sets them apart from Vanguard Veterans, who carry bolt pistols instead, and makes the Guard seem more of a 'different from the norm' unit.
2) Theme weapons: Use the theme of your army as inspiration for a new weapon, simple and effective. Bonus points if it would look really out of place in the parent army, as it's a bit of a detriment to uniqueness if the weapon could feasibly be seen in the original army.
Example: The Frost Axe. It's a frosty axe carried by warriors who hail (I swear this isn't a deliberate snow-based pun) from an ice planet. It would look really out of place in the vanilla flavour codex, which is more universal and unspecific.
Designing a new weapons portfolio
1) Don't go overboard with guns: It's all very well having lots of weapon types, but statistically the more you have, the less unique they will all be. A good rule of thumb is to have 15 ranged weapons or less that can be used by at least 2 units. That should be enough to cover all your bases. You then have room for more guns that can only be used by 1 unit and form part of the unit character.
Remember when writing a custom codex to keep in mind that you want other people to be able to use it easily. Think in your mind that it's not just you who has to memorise all these statistics. Too much codex flicking ruins game pace.
Example: In the Dark Eldar Codex, there are about 14 guns (excluding missiles) that appear in more than one unit entry. You then have Haemonculus gear, missiles (included here as only flyeresques use them), the Mandrake Baleblast, etc.
2) Things you want to cover: When writing up gun stats, keep in mind the gun archetypes. They work for a reason. Don't feel pressured to include all of them if some of them aren't keeping with the army theme so long as this doesn't affect the playability of the army. Some common types are:
2.1) The Troop Gun: You NEED this. Generally around the potency of a Bolter or less. Don't feel scared to go up to AP4 or have 3 shots by the way. It's perfectly doable if balanced by shorter Strength or range. As a rule, I'd say the extremes are 30", S5/Poison, AP4, Assault 3, but not all at once. That's more like an Elite Gun. If you'd like more shots but not Assault, just make a rule that allows the gun 3 shots rather than 2 when rapid-firing or similar.
2.2) The Troop Gun Upgrade: This is a better version of the Troop Gun. Often characterised by a similar name and slightly better stats, or being a Heavy version of the Troop Gun, or both. The classic example is the Heavy Bolter. These are often disregarded by the competitive sector as a unit upgrade for not being able to do much more than the Troop Gun for the points you pay, which is usually about 5. So keep that in mind when deciding what to do with it.
2.3) The Mid-Strength: Not quite the TGU, not quite the AT, this gun is at home fighting both heavy infantry and vehicles. This is a very effective, popular archetype for that reason. Generally no more than +10 points for the pleasure of having one. No more than S7, as any more is technically Anti-Tank territory. Examples include the Autocannon and Missile Pod.
2.4) The Short-Range Anti-Tank: 6-24", S8+ with usually 1 shot, sometimes 2. They all generally have better AP than the Mid-Strength to emphasise their role as specialist weapons, and help justify their slightly more expensive cost. That said, a S10, AP6 weapon shouldn't be too much fewer in points compared to say, the Railgun or Lascannon as otherwise it's very exploitable. To help make up for shorter range, they often overlap with the Special Rules Gun, for example the meltagun and demo charge.
2.5) The Long-Range Anti-Tank: Although usually less effective than their short-ranged cousins, they make up for it in range. Sometimes they can be more expensive than these weapons because of their range, but this shouldn't happen in extremis, as it just makes them less efficient and less tempting than their cousin.
2.5) The Pricey Awesome Gun: The extreme Long Range AT, it's really expensive and usually unjustifiable, most often because it's only been giving one bleeding shot. Try to make yours less of an expensive gamble. It should be expensive, but surely if it's the best of the best it should be effective too?
2.6) The Special Rules Gun: A gun with special rules. They come from all walks of life. Cost them according to their role, and when talking templates think about how many they're likely to wound and their range.
2.7) The Downsized: Teeny-weeny versions of other weapons, in pistol form. Generally round about the cost of the original or slightly less due to the combat bonus.
3) No copying Jenkin's work: If you want a bolter, autocannon, meltagun, etc, play that army or make a variant of it. Try to be ever-so-slighly different whilst still useful.
Examples: Every race in the game has their own slighly different Troop Gun. Eldar missiles have a different anti-infantry profile to Marine ones.
4) Don't re-invent the wheel in combat: You're allowed the Special Combat Weapons from the rulebook, as they are the equivalent of public domain. Try to make up something useful if you want to though. Key emphasis on 'useful.' Even the combat armies don't really deviate too much from the norm.
Example: The Agoniser. A nifty two-combo of power weapon and poison. Dark Eldar in general are good at this.
Original Example: The Rector's Spear. A spear personally blessed by a priest of Sa'maa, so long as the bearer is alive, his squad gains +1 Leadership. 5 points. Useful as it means you don't need to attach a character to your unit to gain more Leadership. Also proves that it doesn't strictly need to be a purely combat bonus, although it helps if you lose.
Bad Example: The Scope Knife. A knife with a targeter on the handle for throwing, it gives +1BS. 10 points. For a combat unit with only pistols, this isn't really too useful, as you're not relying on the secondary shot.
Alright, that's all for now. Check back soon as I outline plans for the Disciples' weapons portfolio.