To get a Fremennik Sword, you must not have completed the quest "Fremennik Trials", as you get it ( after much effort and luck) during this quest. You go down into the area to fight Koschei the Deathless, and you kill him the first 3 times, which is fairly easy. The fourth time, he is much harder to fight. If you die, you have completed this part of the trials anyway. If you win, he drops a Fremennik Sword.

Find and talk to Brundt in the main building in Relleka with the quest icon.

There are a couple I suggest, if your are F2P then train on white knights, if you are P2P train on Yaks (If completed Fremennik Trials quest,) or train on Rock Crabs.

The simplest way of getting to waterbirth island is to talk to Jarvald standing on the west most dock in Rellekka. If you have not completed the quest "The Fremennik Trials" you will also need 1k for travel.