The Cloak of the Helmingas is an exclusive pre-order cosmetic for a reason. No other cloaks look exactly like it, but the Cloak of the West-tower has some embroidery that reminds me of the Cloak of the Helmingas, albeit in gold instead of silver. The Ceremonial Singed Cloak features a silver stylized dwarf, but dyes similar.
Sorry I could not be more helpful, but this is as close as I could get. Perhaps some Rohan cloaks which I have not seen yet feature closer patterns, they seem to have a diverse array of styles.
Night is falling,
So ends this day.
The Road is now calling
And I must away.