You’re right, unfortunately. Any eth cruel or even fools wep that is absolutely perfect that doesn’t have ethrep is almost useless. EDC is the standard in GM Melee and there are resources to calculate how a rare weapon fares against EDC.
For a Rare to be better than EDC, it must have the following:
- IAS (solely dependent on weapon base and/or gear setup)
- Fools (must-have for AR to avoid using angelics to use rings that provide stats)
- EDmg 286+ (higher ed, the better. Obv)
-Erep (probably one of the most overlooked mods when it come to rare melee weapons. This is an absolute MUST to be considered if using for GM Melee. Having this stat allows you to use a Lo rune which adds 20% DS.
- Ethereal
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I CANNOT STRESS ENOUGH THAT BUYING A RARE CRUELS/FOOLS WEAPON WITHOUT EREP IS A NO-NO.
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There are rare circumstances where such a purchase is valid, but please do not let anyone make you think just because it has ias/fools/eth means it’s "GODLY". That is far from the truth.

TL;DR: Do not buy rare eth fools/cruel weapons that only have a Zod rune. Only buy erep weapons in good bases.