There are more ways than one to do actions in this game, for example, to examine a mailbox you can input "look at mailbox", "examine mailbox" and "what is a mailbox?" If you can't do something in the game, try rephrasing your commands a bit.
When you reach the point in the game where you are forced to fight a thief in order to gain access to items in his room, you can finish him off easily by stealing his stiletto using this trick.
Enter the thief's room from the one directly below it, then type "Get stiletto" (w/o quotes). If you fail, simply return to the room below and type "G" to instantly get the stiletto despite not being in the same room as the thief! Now you return to the room above and defeat the thief.