Attended by or causing disaster or inauspicious circumstances.
On the left side; left.
Heraldry. Situated on or being the side of a shield on the wearer's left and the observer's right.
[Source : Answers.com]
Please explain the highlighted words/phrases.
#3 > Attended by = accompanied by
#5 > Stand looking forward. Hold something in your left hand. This is the "sinister" side in heraldry. Now do this in front of a mirror. You will see that to someone facing you, the object is on the right-hand side.
If you hold something in your right hand, this is the "dexter" side in heraldry. It will appear on the left to someone facing you.
Oh, and since you are also studying heraldry, you will be interested to learn that the "baton sinister" was an indication of illegimate birth. Simon Bar Sinister was the villain in the cartoon show "Underdog," which I watched religiously as a child, never knowing his name meant "Simon the B-----d."