Surgical saw
It is a one-handed, powerful weapon that can be found on the first floor of Pembroke Hospital. The saw has a high attack speed and good toughness. Although she cannot deal very much damage, after upgrading this weapon and gaining the ability to suck blood on impact, the saw will greatly strengthen Jonathan. You will be able to get a lot of blood in battle and use it as a vampire skill.
Lupara
It is a shotgun with a smooth barrel, perfect for dealing high damage at short ranges. Plus, it can be quickly upgraded to deal massive damage. The downside to these weapons is the need to have ammo - although it is certainly worth having at least one of these types of firearms in your inventory.
Parabellum pistol
If you are annoyed by the short range of a shotgun and prefer to use the weapon at longer ranges, then the Parabellum is the best choice. This is a very good weapon, useful in boss battles.
Tip: it is better not to use two-handed weapons. It is quite slow in combat, exposes you to attack and is not suitable for effectively absorbing the blood of enemies. Your best bet is to grab a one-handed weapon, pick one firearm, and develop your vampire skills to always get a lot of blood.