Seeing as a third of the enemies in the game are weak to piercing damage I really want to have a competent weapon available to me that does nothing but piercing damage. Currently the only options available are 4 Guns and 1 bomb. The Callahan which is too slow and the Blitz Needle which is even slower (stopping to shoot bothers me). That leaves the Sentenza and the Argent Peacemaker. The problem with these two is that they do a split of piercing/elemental or piercing/shadow. So if I took the Sentenza I would do great against beasts but normal damage against Fiends and vis versa if I took the Argent Peacemaker. The Radiant Sun Shards has the same problem as the Argent Peacemaker (split of elemental/piercing).
So what I would really like to see is a 5 star version of the Antigua that does only piercing damage or a sword that does only piercing damage.
Ionized Salt Bomb is quite good at dispensing Piercing Damage.
As well as the Shock Status.
Also, the Callahan is a great gun if you can use it properly.