> því að trúr skal eg þér í ráðum."
> because I shall (have) faith in you concerning advice."

"I will [be] faithful/trusty/reliable to you in counsels" -- i.e. I
will give you advice you can rely on; you can depend on me to advise
you well here. 'trúr' is the adjective (masculine nominative
singular), rather than the infinitive of the related verb 'trúa'
"believe, trust in, have faith in".

LN