I have 10-20 swords/knives/daggers that belonged to my deceased brother-in-law. Some relate to the Highlander series that was popular in the late 1900s. Does McKay's purchase and sell these sorts of items?

Well, the late 1900's you say? The quickening has begun even now in the early 2000's. But beware because there can only be one. But probably should not bring weapons to McKay's may make people uncomfortable

I would recommend looking for an auction house to go through or even a pawn shop. You are going to get much better prices at both places. Ed mckays will try and rip you off massively.

I would call and ask first but they probably will

Its likely that they will. For that one I would call and speak to someone first. And if they don't you could try selling them on Facebook or a pawn shop

You can ask them if they will take them

They have a lot of collectables. Take them by to see what they'd do. You'd be surprised at the things they buy.