Conversation so far:
What was Richard I of England's occupation?
kings.
What happen in Sicily?
After the death of King William II of Sicily his cousin Tancred had seized power and had been crowned early in 1190 as King Tancred I of Sicily.
Are there any other interesting aspects about this article?
Tancred had imprisoned William's widow, Queen Joan, who was Richard's sister.
What happen after the imprisoned?
he demanded that his sister be released and given her inheritance; she was freed on 28 September, but without the inheritance.
What did he do about not getting the inheritance?
Richard attacked Messina, capturing it on 4 October 1190.
Did he die?
CANNOTANSWER.
What else happen?
Richard attacked Messina, capturing it on 4 October 1190.
After looting and burning the city Richard established his base there.
What else was Richard known for?
Richard officially proclaimed his nephew, Arthur of Brittany, son of Geoffrey, as his heir, and Tancred promised to marry one of his daughters to Arthur when he came of age.

Question: What else did he promise?
Self-contained rewrite: In addition to that, did Richard promise anything else?