I mean is that it though? lol
Pretty sure most people have feet slot occupied by a 4TA(edit: not including base) Herc. -Minus I guess the heavy DDs?
Herc feet have TA+2 baseline. A TA+4 augment makes them TA+6. So TA+5 isn't that impressive.
Here are my herc boots:
TPfeet={ name="Herculean Boots", augments={'Accuracy+10 Attack+10','"Triple Atk."+4','STR+7','Accuracy+15','Attack+1',}}
With the base acc/att+10 on herc feet, that makes the comparison:
Relic+3 has Def+13, hp+24, str+6, dex+13, accuracy+1, att+40, TA-1, TA damage+11%, eva+12, meva+14, mdef+2
Overall, easily an upgrade, but it's a TA loss, and in attack capped situations where survival isn't super important it's likely a slight DPS loss.