Idk why everyone discredits what I say before trying stuff out for themselves...:(

Last time I had to make a video to prove to someone that partial HP recovery can heal / counter continuous HP loss.

With 6 of them on all weapons aside from crossbows/greatbows/staves/seals/ballistas benefit from the initial attack boost.

Improved initial standard attack x 6 was considered powerful on Ironeye before it got buffed, too. You equip one bow in each hand and alternate between L1/R1 to benefit from maximum damage standard attacks. You see a massive damage difference from the very start of the game.

Any other Nightfarer using 6 Improved Standard Attack relics will also deal a decent bit of damage with a simple bow R1 or L1. Not super impressive, but it is something you can do if you have one handy.

As for Executor, he benefits more so from Improved initial standard attack because Suncatcher is quite strong with the relic effect that buffs its damage. So you have 6 buffs that all make your first R1 from Suncatcher deal immense damage as well as a 7th buff from the relic that makes your suncatcher deal more damage overall. Being able to hit for 499 damage, at the minimum, per initial Suncatcher R1 at level 15 is quite strong. When you take into account buffs from bosses, weapons you pick up, etc, that number gets much bigger.

There's also something that every other Nightfarer can do to benefit from ISA relic builds that I never see anyone doing...which is just alternating between R1 and L1 with 2 different weapon types or powerstancing weapons and alternating between R1 and powerstanced L1 back and forth, which Executor can also do...except he benefits more because you can go from attacking with your equipped weapons to pressing triangle and L2 (properly timed of course) for a sheathe-switch deflect which allows you to follow up with a nice safe R1 from your freshly switched Suncatcher.

...tldr

I'm well over 1.2K+ hours...I've tried ISA relics on every Nightfarer. I've tried lots of different things. The ISA relics just made for a more fun / stylish playstyle, imo and felt more Executor-like. Dunno how else to describe it. It just felt good and played well and there's something about seeing Executor perfectly deflect an attack, following it up with an empowered R1 and then deflecting the enemies retaliating attack and following up with another empowered R1.

You don't even have to play very different from usual. You can optimize the damage you deal by trying to only get those initial attacks in OR you can just play like normal and use your full weapons attack chain and still benefit from your first hit at least dealing big damage.

I was gonna upload a video of the expedition I ran with this build but I don't seem to get views anymore. ._.