I was putting together a game for Dark Heresy the other day and this came up....

If a creature has the trait multiple arms and has the talent Lighting Attack

does the creature get 3 for the lighting attack and two for the multiple arm trait?

I and my fellow players are guessing that since lighting attack is a full action that it would only be

3 and if so multiple arm trait seem superfluous

No actually, because you can attack as a full action then attack with your off hand extra.

I believe that the maximum number of attacks people can pull off in a turn is like 5, if they use the Furious Assault "Convert a reaction" to an attack as well. Genestealers can do that