Makoto's 4* Weapon is actually good & its activation condition is still misleading
This was known for a while now, but now we can see for ourselves. In fact, I am having a difficult time getting this to not activate. It keeps activating when the battle starts and I'm not even sure why. "When Makoto buffs an ally" seems to also include himself as an ally. Moon Phase also seems to count as a buff. Which he is giving himself constantly. So. This may surpass the Ex Machina weapon description.
Additionally, he receives both damage buff weapons from the weapon description (shown in comments). Which, at max forge, is actually basically identical to the damage boost of the 5* weapon. So. The 4* weapon damage boost is actually technically better, because for the 5* weapon it only activates off of attacks with 4 hits, unless you have him at A1, it won't activate for S1 usage. S1 isnt his big damage, but it's still something to note.
That means the only difference between the 4 and 5 star is the 5 star giving 16.3% Crit rate (and the typical 5 star Attack difference). Which is very good! But the gap is significantly lessened, as their damage boost numbers are equal.
I and others perpetuated the thought early on that the 4 star weapon was useless. I apologize for that one. The game never ceases to humble you by showing you that you can't take what it says seriously until you test it yourself.