i got two little digs on the edges of my trowel which i got out with some fine sandpaper.this blunted my trowel(one each side).i took it to a tool sharpening shop and hes "put an edge "on it.he said he couldnt sharpen it like a knife but hes put an edge on each side.will this cause me problems,ive got to use it tommorrow,hes kind of squared off each edge.advice please not been plastering that long(5 yrs).please can i have some serious comments