Clk,
As your blade doesnt move too fast, it would be fine to sharpen. The key is to get the cutting angle right. You could make up a small jig that would hold the blade & allow you to move it across the oil stone at the same angle along the full length of the blade. That way the cut would be uniform.

SRJ,
Be careful sharpening blades on lawn tractors. They are normally very thin blades & suffer from metal fatigue by the time they need to be sharpened. I have had a few break off by cracking through near the bolt hole. First I knew about it was when it started shaking bad. When I looked there was a hole throw the side of the deck & no blade.
My tractor slasher (12' pto driven) has 2 spindles & the blades are 1/2" thick. They get sharpened with the angle grinder.

__________________
Grumpy Old Diesel Owners Club group

I no longer question authority, I annoy authority. More effect, less effort....

1967 230-6 auto parts car. rust bucket.
1980 300D now parts car 800k miles
1984 300D 500k miles
1987 250td 160k miles English import
2001 jeep turbo diesel 130k miles
1998 jeep tdi ~ followed me home. Needs a turbo.
1968 Ford F750 truck. 6-354 diesel conversion.
Other toys ~J.D.,Cat & GM ~ mainly earth moving