The skaven cards acually say skaven on them. Is this a keyword like scout or knight and if so does it have an ability besides what is written on the card..again like scout. Thx in advance.

It has no specific effect but some abilities might use the trait, like Grey Seer Thanquols (He gains one power for each Skaven unit (Card?) in play) So any card with the Skaven trait would boost his power.

I think the should answer the question