One of the most important things is not to describe your 'defensive' tools in public on the internet. General advice is to get away and get help. Alarms can be useful but make sure you can grab them - no good in a drawer somewhere. Also be aware anything you use could be turned on you AND may make the situation worse. An attacker may actually not intend harming you, may be purely after cash or belongings but use something against him, and he then stabs you defending himself.
I've had it made quite clear to me that I should be very careful not to hurt any attacker.
As I've posted previously this week, the advice people trained to fight give is the same "try get away first, only fight if you really have to".
Mace/pepper, tasers, stunners and knives are all illegal to carry which works both ways - any attacker who carries a weapon faces a charge just for having it, or having their sentence increased just as commiting a burglary with tools is.