These are only some random tips and tricks I figured out after a few playthroughs of the game. Don't expect too much out of the guide, I'm just writing it for fun, but hopefully some of these are helpful to someone. These are in completely random order, but I'll do my best to avoid spoilers, especially of anything story-related.

The weaponry system in Lies of P is honestly less complicated than many soulslike games. However, there are a few quirks and unintuitive mechanics I'll talk about here.

• Weapon damage scales off of a combination of three different stats: Motivity, Technique, and Advance. Generally speaking, Motivity represents strength, Technique represents dexterity, and Advance represents special or elemental damage. The important thing to note when creating your build and investing Ergo into your stats is that Motivity and Technique only scale physical damage (what almost all weapons inflict). Some weapons deal a combination of physical damage and another kind of damage, which could be fire, acid, or electric. These special kinds of damage scale with your Advance stat, but not with Motivity or Technique. This means that Motivity or Technique builds are generally more flexible, especially in the early game. These stats also affect your Legion Arms, but I'll cover that in a bit.
  
  
• There are two kinds of weapons in the game, Normal weapons and Special weapons. Special weapons can generally only be obtained by trading special Ergo chunks dropped by some bosses with the NPC Alidoro, or with his replacement Hugo. Save your special Ergo. Each special piece is unique to a run, so if you sell it you may have to do more playthroughs than you would otherwise to collect everything.
  
  
• Normal weapons can be disassembled into two parts: the blade and the handle. Any blade can theoretically be paired with any handle, but certain combinations work better than others. The damage scaling that a weapon has is tied to the handle only, not to the blade. This means that you can have two weapons with the same blade but different handles, which have completely different stat scales. Incidentally, each handle has stat scaling using letter grades. A - symbol means that that stat does not affect the weapon at all. D is the lowest grade, than C, B, A, and finally S. S stat scaling can only be achieved by using Cranks.
  
  
• Cranks adjust the stat scaling on a weapon in various ways. There are four kinds of Cranks. First, Motivity Cranks will raise that handle's Motivity scaling, usually by one letter grade. However, a Motivity Crank will also decrease that handle's Technique scaling by a letter grade at the same time. A Technique Crank does exactly the opposite: it raises the handle's Technique Scaling, but also decreases its Motivity scaling. Advance Cranks raise the handle's Advance scaling by a letter grade, and do not affect any other stats. This may make putting an Advance Crank on everything seem tempting, but remember, Advance only affects special damage, and won't have any effect on blades with only physical damage. A Balance Crank removes the effects of any other cranks.
  
  
• Because of how your character's stats scale, in the late game (I would recommend an Ergo level > 150 at least) you will likely get better damage out of your weapons by keeping Motivity and Technique roughly balanced, and likewise stat scaling on your weapon roughly balanced as well, as opposed to going all in on one damage stat.
  
  
• There's one more variable that affects how well your weapons function, and that is Stabbing versus Slashing moves. Handles determine the animations of your weapon's attacks, whether it moves like a spear, a sword, or something else. Depending on how they're shaped, some blades are designed to do slashing attacks, some are designed to do stabbing attacks. This means that handles with slashing animations will work well with slashing blades, and stabbing handles will work well with stabbing blades. You can tell what kind of moves a weapon will have and how well they'll work by a pair of symbols: a '-' means the weapon has no attacks of that type, a '=' means that the handle and blade match, and a '\\//' means that the handle and blade are mismatched. If a handle and blade are mismatched, the attacks using that kind of animation will deal less damage.
  
  
• What is generally recognized as one of the best blades in the game, besides Special weapons, is the Bone-Cutting Sawblade. It may not look like much, but it has surprising reach, decent damage and stagger, and can be found fairly early (in the Malum district). It also works well with several handles and different builds. I recommend using it with the Krat Police Baton handle for a Motivity build, and with the Master Chef Knife handle (once you obtain it) for a Technique build. I like to experiment with different weapons, but the Bone-Cutting Saw has carried me through many boss battles, including the final boss on my first playthrough.
  
  
• Legion Arms are Lies of P's options for offhand 'support' weapons. All Legion Arms except for the base one have three tiers of upgrades, each one enhancing that Legion Arm's special attack in a unique way. There are a limited number of Legion Calibers, the upgrade materials, in the game, but don't stress too much- you can fully upgrade everything in NG+. Each arm has its niche, but Puppet String and Aegis are the most versatile and easy to use. Personally, I also like Deus Ex Machina for dealing with many minibosses.

• Defensively, you generally have two main options in combat: dodging and blocking. By the end of the game, you should try to become proficient in both. Dodging is (for me at least) slightly easier, but blocking can let you use a Perfect Guard, which can do things like stagger your opponent and eventually break their weapon.
  
  
• A Perfect Guard occurs when you tap the guard button just before an attack hits you. It's pretty easy to tell if you were successful or not. If you want to practice Perfect Guards, square up against one of the stationary boxing puppets. One is locate next to the Stargazer just outside the first boss room, and one is located in the courtyard of the hotel. Almost every enemy weapon in the game can be broken with enough perfect guards, including most bosses. In the case of the bosses, it usually takes long enough to not be worth it.
  
  
• This is a somewhat obvious tip, but not all enemies respawn. Many of the battles against stronger enemies do not need to be repeated, and most of these stronger enemies drop unique and/or valuable items. Kill everything at least once. Besides valuable items, this will also allow you to explore everywhere through the level, and accumulate enough Ergo to stay at a reasonable power level as you advance.
  
  
• Butterflies are special enemies that appear in certain areas when you approach them, heralded by your lantern turning red. These enemies only run away and do not attack, save for the largest yellow butterflies, which can perform a shockwave attack that knocks you back if you get too close. Butterflies do not respawn, and always drop one pre-determined useful item. Some butterflies appear in awkward places however, such as nearby to a group of enemies, or on a narrow platform which makes attacking difficult. One yellow butterfly in particular (if you've been killed by it, you know the one I mean) is perfectly positioned to shockwave you off a small bridge to your death when you try to attack it. For the more irritating of these, I recommend using the Falcon Eyes Legion Arm, which lets you attack from a safe distance. The butterflies don't even have enough health to consume much of your Legion attacking them.
  
  
• In general, Puppets are weak to electric damage, carcasses are weak to fire, and humans are weak to acid. Obvious exceptions exist however, that's just a useful rule of thumb.

• There is no known use for the overgrown Stargazer nearby to the Pilgrim's Path. It has been theorized it will be used for DLC content.
  
  
• You can reset your level, P-Organ, and Legion Arms in two different locations. The Saintess Statue is the obvious one, but you can also reset things by interacting with the Gold Coin Fruit tree after harvesting fruit.
  
  
• With each NG+ cycle, the P-Organ gains new nodes, allowing for many powerful new buffs and useful QoL improvements like extra weapon and Legion Arm slots.
  
  
• In NG+, the Saintess Statue Stargazer and the Gold Coin Fruit tree are automatically unlocked as soon as you reach the hotel, allowing for easy resetting. The door out of the Saintess Statue's room is locked however.
  
  
• Eventually, you will have an infinite supply of Hidden Moonstones, Crescent Moonstones, and Half Moonstones available to buy. Full Moonstones are limited however, as are Dark Moon Moonstones and Moonstones of the Covenant.
  
  
• Eventually, the first chapter will become permanently locked. Make sure you collect everything you want from it early on. Other chapters can be explored at your leisure.
  
  
• If you're any kind of completionist, once you reach the Grand Exhibition don't kill the area boss until you find an NPC in the area named Belle. Otherwise you'll get locked out of a questline. I learned this the hard way.
  
  
• I'll try to avoid spoilers in this tip. If/once you acquire Alidoro's Cryptic Vessel, decrypt the vessel immediately. Do not talk to Eugenie until you do! Otherwise her questline breaks, for some bizarre reason. Again, I learned this the hard way.