The current edition of Dungeons and Dragons has a rather large weapon
list. However, I there is usually a tendency to focus on particular
combinations such as sword and shield, longsword, greatsword and so
on. However, there are many other weapons that provide for their own
unique options. For this reason, I hope to inspire more variety of
use.
Tactical Reasons
The typical go to examples are swords. They are cool, they are iconic
and they got good one hand a two hand damage (longsword and
greatsword especially). However, many other weapons have the reach
property that gives them a bunch of tactical options that swords
don't. Shields also give tactical options due to the increase in
armor class, but similar things can be accomplished through good
armour. The thrown property is also useful, especially so when extra
attack isn't present (I let players use extra attack).
Remember, Not Everyone Can Use Swords
I often forget which weapons are considered simple and which are
martial. However, this plays a big role. Certain classes cannot use
many weapons so remember to keep this in mind when choosing weapons
for characters. No one that can use a war pick would want to use a
sickle unless in some strange circumstances. However, not everyone
can use a war pick. The result is that most non-trained people should
be using weapon such as axes and spears.
Incentive
A player may really want to make a shield and spear fighter but the
math of the game moves them away from their desired character. I
mean, as written a thrown weapon isn't THAT useful (you can't even
throw multiple darts or javelins) but it does give an extra
advantage. However, the d8 vs d6 damage of a longsword may be too
tempting. If this is the case, a simple magic item can fix this
easily. A +1 spear is all that's needed to give the same damage
outcome and to make the player happy. Just don't treat it as a magic
item and everything is fine (otherwise, the +1 spear has even more
benefit over a longsword). You could let the player buy a +1 spear as
well. Spears are naturally cheaper than swords in the game so why not
a +1 spear? It will still be more expensive than a longsword, so the
advantages I feel are earned.
Changing Appearance
Above, I mentioned how adding a +1 to an item can work. You can also
have a custom spear made for the player that has the properties of a
longsword but the appearance and piercing damage of a spear. This
solves the problem and also doesn't force the player to spend more
gold on an item to get what they want and as a result sacrificing
other elements of their character.
Brand New Weapons
Some weapons won't be included in the table but are close enough to
another weapon. These are easy to add by just describing particular
details of a weapon that already exist. You can also add details
about particular weapons you are using. It could be that your player
is still using a longsword. However, it's not just a longsword now.
Now it's a grosse messer or has a ring for hand protection. There is
more to a weapon than just damage so don't forget to describe certain
things that make your weapon unique. I remember I had one player who
had small notches on the blade that all came from important events to
the player character's history. It may not directly contribute to
combat, but it sure contributes to roleplay and that is equally or
more so important (depends on the player, of course).