Soul eater is the best anime I've ever seen, it's also a manga
About half the cast can turn into weapons, and the rest are miesters,
Kishin and witches. The plot revolves around the
DWMA, defensive weapons and miesters academy or something like that. The headmaster/ruler of the DWMA is Lord death(or shinigami) he is a wacky grim reaper who can perform the "reaper chop" where he dents your skull with a gigantic glove
the main characters are Maka and her weapon, Soul who can turn into a battle scythe,
Death the kid, the awesome symmetry-obsessed son of Shinigami, with Liz and Patty, twin pistols,
Blackstar, the "ninja assassin who will transcend god" and
Tsubaki, the easy-going enchanted sword of Blackstar
as well as a whole bunch of bad guys! you have to watch it to appreciate it. (but beware of "legend of the holy sword" it gets obnoxious)
Example:
Blackstar: can we still be friends?
(pause)
Soul: Of course! we'll always be friends!
Blackstar: Oh, Soul!
Soul: Blackstar!
Blackstar: oh soul!
Soul: Blackstar!
(this repeats a few more times)
Maka: they need professional help
BOOM!!!!!
(kid has basically exploded them)
Kid: oops, I'm sorry.
My finger slipped
~Soul eater