The Riddler.

[Lily]

Yay! *happy dance*

I wanted that sword replica... 

[HeadInAnotherGalaxy]

Tis ok, you can have a flying bulldozer instead. 

[Nightfire]

Hahahahahahahaha!!! Okay, then.

"Thin, silver and sharp,
I most certainly am not a harp.
My hilt is leatherbound and firm,
And when a warrior wield me, then I am quite stern.
I have been used by rogueish hares,
And squirrels from the north without any cares.
I can be easily concealed, hard to see,
Yet when in action, invisible I cannot be."

[Leatho Shellhound]

Is it Martin's sword

[daskar666]

...claymore?

[Gonff]

Martin's sword was my first thought too, but has it been used by hares?

[daskar666]

It was used by Laird Bosie but I don't remember him as particularly rogueish...at least in hare standards.

[Matthias720]

I'll say it's a dirk.

[Redwall Musician]

I'll say it's a dirk.

Yes! I agree with Matthias.

[HeadInAnotherGalaxy]

I can be easily concealed, hard to see,
Yet when in action, invisible I cannot be."

Tis a Sgian Dhu.

[Leatho Shellhound]

The last animal to use the sword was a hare in Doomwyte.

[Nightfire]

I'll say it's a dirk.

Matthias, you've got it! It's a dirk, used by both the hares of the Long Patrol, and Rakkety Tam and Doogy.
Okay, next riddle.

"I am calm, yet I am wild,
Sometimes I act just like a child.
Raging, churning, crushing,
Serene, gentle, and lulling.
I can crumble mountains over time,
Wend through endless lands sublime.
I am blue, turquose, or clear,
Some fall in love with me, while others fear."

[HeadInAnotherGalaxy]

Tis water.

[Nightfire]

Darn! You got it! I guess I'll have to try harder on the next one!

[Lily]

*Is hit by flying bulldozer*

I guessed the last two too!

*Is hit by more bulldozers*