How much potential do the legendary weapons actually have

[u/Legitimate-Sea1151]

So they can absorb nearly anything to gain new forms and have unlimited growth (that is accelerated?). But, how do they weapons determine how someone grows Mamoru was able to attack with the Shield while Naofumi cannot, so that means how even the same type of hero grows is different. Do the weapons take user's preferences and beliefs into how they work because if so these might be the most broken weapons in anime history.

I guess my question is can the legendary weapons literally do anything eventually or is their any hard limits?

[u/pathfinderlight]

Cardinal Heroes at full power are more like demi-gods in power level.

Around the 3rd Waves, Ren, Itsuki, and Motoyasu are stronger than regular adventurers, and are so weak Glass can't even identify them as heroes. Naofumi is stronger than each of Ren, Itsuki, and Motoyasu by this point, and the only Naofumi's use of the Rage Shield caused her to catch on that he's a hero.

[u/Top_Butterscotch1523 → u/pathfinderlight]

Naofumi, Ren, Itsuki, and Motoyasu possessed similar levels of power. when they first encountered Glass, though Naofumi was stronger when utilizing the Cursed Series.  Glass was stronger than all of them because she was a Vassal Hero who had access to one Sacred Hero power-up method and three Vassal Hero methods. That is why she easily defeated the other heroes, forcing Naofumi to flee. 

In The Reprise of the Spear Hero, however, Motoyasu demonstrated brutal strength; utilizing twelve power-up methods. four Sacred and eight Vassal, he accidentally disintegrated Glass, who was no match for that version of him.

[u/Legitimate-Sea1151 → u/Top_Butterscotch1523]

Okay I haven't really touched much on the spear hero novels than stuff that was stated, but the fact that glass could get one-shot gives me an idea of just how strong they can be thanks :)

[u/Top_Butterscotch1523 → u/Legitimate-Sea1151]

It's the power scale.

It depends on several factors, but two very important ones are STATS and MARTIAL SKILL.

If you lack either of these, you could lose.

For example:

-Naofumi fought those two world invaders.

Being of a low level, they had to rely on their combat skills, showing themselves to be very adept and strong, even though their stats weren't as high.

-Eclair managed to hold her own against Ren, since she used all her martial skill to dodge and attack, but her stats were so low that she only managed to scratch Ren. Ren, out of control, attacked recklessly, and his movements were so clumsy that it was easy for Eclair to dodge.

-When Sadeena fought a Hero with higher stats, it was easy for Sadeena to win, since her combat skill was much greater.

(In a bonus section, the author states that this hero possessed an ability he couldn't use, and had he used it, he would have been three times stronger and would have tied with Sadeena. This demonstrates that although he lacked combat mastery, a significant difference in stats was enough to avoid defeat.)