In the last line, Alu is most likely a reference to the runic sequence of Ansuz Laguz and Uruz. These three runes put together are commonly associated with magical charms. It's possible that Alu in this context has no linguistic meaning other than it being a charm. At the same time, the entire line "Alu Is Urki" looks similar to a line found inscribed on the Eggja Stone, though this particular panel is partially destroyed. This wouldn't be the first time Heliung used the Eggja Stone as a source for lyrics.