One of the most memorable features of your condolence note should be "a kind word." Fill your heart with gratitude, admiration--even awe, and pour it out like a sweet balm.
I have tried to adopt "balm pouring" as a lifestyle. It makes life sweet, but it is an art. At home in the morning, there are times when I pour fresh, fragrant coffee from the French press into my mug and keep pouring beyond the rim! It's fascinating to watch the physics of capacity (enhanced by a fresh-from-bed brain) as liquid and brim strive earnestly to preserve the delicious nectar.
As you draft your note, pour with a free hand. Kindness--like a cup--has a brim; you will feel what is excessive and your finished message will glisten with light.
...To heal by grace-kind and caring,
we smooth the splintered plank,
dull the point,
and gentle cheerless corners of
the sharp-edged world.