With the second season of The Rising of the Shield Hero anime now over, the fanbase has collected their thoughts and formed a variety of different polarizing opinions on it. The second season of the series attempted to blend elements exclusive to the original Light Novel, the Manga, the Web Novel, and even its own elements into one story, and no matter what the end result was, this choice was always going to make some aspects confusing to viewers.
One example is the Vassal Weapons, otherwise known as the "Seven Star Heroes", as the concept of Vassal Heroes and how they relate to the Cardinal Heroes is still one of the most commonly asked world-building questions. So, to hopefully help clear some things up, let's look at some of the strongest Vassal weapons seen in all three versions of TRotSH and elaborate a bit more on how they work.
8 The Vassal Book
First up is the Book Vassal weapon, which might surprise some people considering how strong it seems. This weapon is used by Kyo Ethnina, who is one of the Vassal Heroes users from the world that Glass, L'Arc, and Therese come from (let's just call it Glass' World). Now, Kyo isn't around nearly as much in the anime as he is in the manga, but the Vassal Book still has a lot of its abilities and powers shown off compared to some other Vassal Weapons.
But, remember, a lot of this has to do with elements outside of the Book itself, such as Kyo using the Guardian Beasts' energy, being able to take over a new body after death, and his cold-blooded actions that come from his mentality of seeing this world as a "game" much like the other Legendary Heroes do. But, on it's own, the Book Vassal Weapon is a great support-type Weapon. Although, its Power-Up Method, Revised Edition, is still a bit confusing and seems noticeably weaker than the methods a lot of the other Vassal Weapons use.
7 The Vassal Scythe
Let's move on to an exciting Vassal Weapon, the Vassal Scythe. This is, of course, the Weapon used by L'Arc Berg Sickle, a fan favorite character. Now, the Scythe is a fantastic weapon visually, obviously, as its appearance is commonly associated with the concept of Death or the Grim Reaper. And, in the RotSHor most other isekai settings, this assumed strength is usually the real deal.
For one, it seems to be primarily a weapon meant for offense with fantastic attack power. Two, its Power-Up Method, Spirit Enchant, is incredibly similar to one of the Power-Up Methods for the Legendary Spear, both of which are crazy strong. And third, The Scythe seems to have a lot of methods of getting past any type of defense or obstacle, as L'Arc has shown a skill that uses the enemy's defense to deal equivalent damage, a skill that launches a spinning disc of energy from afar, and even AoE tornado-type Skills as well.
6 The Vassal Hammer
The Vassal Hammer is a Weapon that both anime and manga fans may have forgotten about. It hasn't been explored much in the series, save for the fact that it was previously wielded by one of Raphtalia's ancestors named Natalia. Funnily enough, in the Web Novel, it's actually Raphtalia who eventually becomes the wielder of it (but the anime and manga seem to follow the Light Novel).
In terms of its use as a weapon, the Hammer has one of the most absurd Power-Up Methods, Weapon Form Synthesis, which allows the wielder to copy the unique abilities of different Hammer Forms and "paste" them onto another Form. And, the fact that it's a Vassal Weapon of the Legendary Shield but is also a "counter" to it with its impact-type damage, means that even Naofumi with all of his different abilities would still struggle against it
5 The Vassal Fan
Yet another Vassal Weapon from Glass' World, it's the Weapon used by Glass herself, the Fan! There are a variety of reasons as to why the Fan is this high up. For one, it's particularly strong with Glass, as she comes from a race of Spirit People who can be buffed or debuffed with Skills/Items that focus on SP (AKA Soul Power) recovery. Because of this, Glass' own innate talents work in synergy with the Fan's Power-Up Method that seems to absorb the magic residue exuded from enemies as they attack.
Two, the Fan has a variety of different moves that work in a variety of different disadvantageous situations. Like L'Arc, she has a move that uses an enemy's defense against them, a projectile attack, and plenty of AoE attacks. But last and most importantly, both the Martial Arts that Glass learned in her youth and the innate ability of the Fan both make it so that Glass has more of an advantage the longer the fight goes on.
4 The Vassal Katana
The Katana Vassal Weapon is yet another one that anime fans recently became acquainted with, as it's the Vassal Weapon that "chose" Raphtalia when they were thrown into Glass' World. As a Weapon, the Katana bears a lot of similarities to the Scythe. For one, it's almost exclusively an offensive-focused weapon, with a lot of skills that focus on high-damage, high-speed slashes in exchange for almost no defensive abilities.
Two, it has a lot of different Skills that let Raphtalia attack different facets of the enemy, such as Skills that drain MP, HP, SP, or one that even reflects a Skill back at the attacker. And three, its Power-Up Method (called Refinement), like the Scythe, is incredibly similar to the Legendary Spear, and both methods are absolutely absurd.
3 The Vassal Mirror
Moving onto the Mirror, yet another Vassal Weapon that hasn't been seen for too long or explored at length, but from what fans know from the manga, LN, and Web Novel, is absurdly powerful. Not only is the Mirror another weapon based around defense like the Shield, but it's much more focused on "reflecting" attacks back on the attacker as well seems to use a lot of trickier gimmicks thanks to the concept of a "mirror" having a lot of applications such as light refraction, acting as a "gate", and more.
The previous user of the Vassal Mirror was a reincarnated individual named Albert who ended up being used by Kyo. Now, Albert was already strong, but the thing is he never even used the Mirror's Power-Up Method, Culinary Boost. While this Method is simple, it's a bit hard to explain, but basically, food the user cooks can provide permanent stat bonuses as well as give the user and those who eat the food something called "Food EXP" when eaten. But, because Albert didn't want an overweight "harem", he never used it.
2 The Vassal Projectile
Ah, the Projectile Vassal Weapon, otherwise known as the Weapon that finally gave Rishia a way to actually fight. With the Projectile Weapon, Rishia can fight from afar and use her naturally intellectual mind to outsmart her opponent.
The Projectile Weapon, like the name suggests, can take the form of basically anything that could be used as a "projectile", from a throwing knife to a gun, and that's its strength. But, more than that, the Power-Up Method, Microtransaction Enhancement, literally makes other Power-Up Methods better or more likely to succeed based on how much "G" or money is put into it.
1 The Vassal Staff
Last up and top of this list is, of course, the Vassal Staff. And, surprisingly enough, the user of this Weapon was arguably introduced before even the Cardinal Heroes introduced themselves, as it's held by Aultcray Melromarc XXXII (AKA "Trash"). Not only does this Staff inherently boost Magic Casting and massively reduce the time casting takes, but its Power-Up Method, Magic Rank, allows the user to boost the efficiency of their own spells or the spells of any of the other Heroes as long as they work together.
And, in a world of Magic like this one, especially since this sort has a "Soft Magic" system, a Vassal Weapon that is focused on buffing Magic is of course the strongest.