Its passive is called Desert Pavilion, and it has the following effects — and with basically full uptime:
The wielder gains 24% of their EM as bonus ATK for 12s. Nearby party members also gain 30% of this buff for the same duration. Multiple instances of this weapon can allow this buff to stack. This effect also triggers even if the wielder is off-field.
It has good scalings, but there aren’t many characters that want it. Plus characters that can make use of both EM and ATK have generally better weapon options. For instance, Favonius Greatsword is a much better option for Sayu because of its Energy Recharge and passive. But she can also use Aquamarine since she scales from both EM and ATK. And if you already have more than enough Energy Recharge on Sayu, then Aquamarine is a great option. This is also the case for units that can also make good use of Aquamarine — better weapons exist, but it can also be situationally better. Here’s a more detailed table of the synergies between Makhaira Aquamarine and every playable claymore user.
Good means that the Aquamarine works well with the character, but it’s not among their best 4-star options. Decent means that it works on the character, but there are other better options (usually other 4-star gacha or craftable weapons). Not recommended means that it doesn’t synergize well with the character – or there are significantly better options.
