Regarding the Sommerswerd, I keep it with me through the Kai series (2 - 5) as well as through books 6 - 8 in the Magnakai series. However, in Book 6 I only use it when I'm not in public. The S-swerd is helpful in Castle Death and pretty much critical at the end of Book 8.
In Book 9, with the Darklords on the march, I have it returned to Sommerlund and ask Banedon (offscreen) to bring the Dagger of Vashna in its stead so I can have one nasty (but less recognizable) magic weapon. After I kill the Zakhan with i, I let Banedon take it back to Sommerlund for safekeeping.
In Book 10, I carry no magic weapons, though I do carry a crapload of healing and the Super-Alether from Book 3. I do this in order to deal with Tagazin and Roark without fighting Tagazin directly as well as so I can fight the Chaos-master with the Broadsword. Oddly, I don't use the Super-Alether against him. I save it for the Villains of Sommerlund.
I'm thinking next time I'll take tke S-sword with me through the whole M-kai series and in those places it asks if I have it, I'll add the words "and wish to use it." Assuming you don't choose to use the Sommerswerd, a better bet is the Psychic Ring. If you notice the combat, when you use the Psychic Ring, Kimah is suddenly not immune to Mindblast and Psi-surge.
In Book 9, with the Darklords on the march, I have it returned to Sommerlund and ask Banedon (offscreen) to bring the Dagger of Vashna in its stead so I can have one nasty (but less recognizable) magic weapon. After I kill the Zakhan with i, I let Banedon take it back to Sommerlund for safekeeping.
In Book 10, I carry no magic weapons, though I do carry a crapload of healing and the Super-Alether from Book 3. I do this in order to deal with Tagazin and Roark without fighting Tagazin directly as well as so I can fight the Chaos-master with the Broadsword. Oddly, I don't use the Super-Alether against him. I save it for the Villains of Sommerlund.
I'm thinking next time I'll take tke S-sword with me through the whole M-kai series and in those places it asks if I have it, I'll add the words "and wish to use it." Assuming you don't choose to use the Sommerswerd, a better bet is the Psychic Ring. If you notice the combat, when you use the Psychic Ring, Kimah is suddenly not immune to Mindblast and Psi-surge.