Consider Heaney's comment "...the poem posses a mythic potency"

The massed treasure

was loaded on top of him: it would travel far

out into the ocean's sway ...

No man can tell,

no wise man in hall or weathered veteran 

knows for certain who salvaged that load.

The above passage pierces inside you. The magic of the words pierce inside of us, they bypass culture, overlook years and years, blur the edges of myth and reality until they overlap, and finally they reach the inner depths of our being. Something in those words, can drag us back over the chasm of time and bring us to the exact location of Shield's burial. The word potency reads as "the power of something to affect the mind or body" (Google). I think that what Heaney is hinting at is the poem's intense power to drag you into the poem itself. We are not just contemplating the words, but we are experiencing them. Also, based off of my reading of the intro, I believe Heaney is acknowledging how the poem seems to probe or tap into your emotions. When we hear and experience the death of Shield Sheafson. We feel the grief and deep impact of his death from somewhere deep within us. The poem not only has the ability to take us on its fascinating journey, but it also allows us to feel the journey. For a brief moment we feel as if we are Shield's closest warrior band mate and we are for a split second are mourning as well. I believe that this "mythical potency" is the mark of great literature.

The Presence of a 'Warrior Code' found in Beowulf

This 'warrior code' weaves its way throughout the Beowulf poem. The warrior 'code' itself is hard to pin down. However we often see characters behave in certain ways in regarding to war, battles, strength, and boasts and the poet gives credit to the characters who have good battle prowess.  I feel one of the clearest examples of the 'warrior code' spelled out can be found in Beowulf's speech:

It is always better

to avenge dear ones than to indulge in mourning

For every one of us, living in this world 

means waiting for our end. Let whoever can

win glory before death. When a warrior is gone,

that will be his best and only bulwark (ll. 1384-89). 

In addition, there are other places in the poem where the reader sees this 'code' not merely spoken about, but rather actually played out in the lives of the Danes. Two clear examples of this can be found in Beowulf's skirmishes with Unferth. In one of his story-tellings Beowulf expalian to Unferth that
"We'd [Beowulf and Breca] been children together and we grew up /daring each ourselves to outdo each other, (ll. 535-6)" From these short lines we find an example of a code or cultural value that states 'one man, if he wants higher status, must outdo the other man' It seems this code is so strong, it impacts and governs even the children.