Dragoon Lance is her best in terms of raw Attack power.
Gae Bolg is her best weapon as a Sentinel for the effect (Improved Counter), but lower stats and is probably your best bet IMO because of how useful Sentinels are later in the game. --- Impossible. You can't get killed 9.5 times out of 10. You mean 11 times out of 20. Or you mean 95% of the time. But not 9.5/10. - NInjaZiru
if you are making her a sent. than consider using the gae bolg. it has a good balance of strenght and magic and also has improved count 2. im using the pandoran spear so i can have her as a SAB. it has alost the same stats as the gae bolg but instead of counter it is improved debilitation.