Euphemus the champiom swimmer

Anyone else find the death (murder?) of Euphemus rather vague,not explicitly stated?
He jumps in the water after Acastus,armed with a knife but it´s eventually Acastus,unarmed mind you, who gets the upper hand,killing (strangling him? stabbing him?).So Eupehmus drowns I mean,the Argo had plenty of bows,arrows and javelins that they could have used to kill Acastus then and there ,even without Euphemus Why waste such a good character?
and besides,where on earth did that knife the other argonaut seated next to Euphemus hands him during the fight ever come from????
Cruel fate for such a brave and ,above all,loyal argonaut(jason simply orders his body dumped back into the ocean,thus tritely justifying a burial at sea)
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