Skarphedin  IMO was speaking jocularly but appreciatively the alternative I saw to be "that will come in handy"  and he grinned - he was a son talking to his father and grinned, well with his teeth (you will recall) he could not simply smile - you grin with teeth like that  (JMO)

 

My Bad - I did not see the plural of weapon

 

Where he is  getting the reply - they think he is looking for a poor clapped out old carthorse who has escaped and they sent him to Kol to see if HE has seen the "horse" - they are unaware of Atli's intent (they will find out later)

 

Hinn veg værir þú undir brún að líta,"   well that I sort of "Got round" by seeing it as from another Saga - Egil;s actually  the brows were an important means of conveying expression  - hedge of the eyes - and the way I see it - Atli had "beetling" brows in the style of Egil and he glowered out  from under them in a way that implied he was not to be "messed" with - I apologise for the circumlocution but that is what I "saw" in it

 

I hope at least some of this helps

Patricia