Code:
dqdEcaGAjrTlPKxlsQzks0SHCtrc3wu7ufTx0UPQ9lP4NsImmvQFl0GLu1WPuheQYXeX5ePYcHQAXsPwUepuk6PklJe9CbhMIPsQjdLPdUOifxfQ0LjUov(Ru16ejzZQW2LkFtsLVkj4ZK03Lu60QAAssgNKqJxKsNeQ4wsHRrcNxLSnjPEMiv9ykzMqnxMdJdJAoSpuzN3c(oHZGqCgl47eD5vvLskIycpBKCZzSGp6duZfatbOMdl2RII1s85urXA7pkMSWvbXKA8CftivGeGlce4GYRQkfQ5c2ccHdgxsDvSUQU5WCfd8rpNco4Yw4KoXdCbxBPt8WChhFA56BI309d3MntZgxWwqOttw44KoXdCnJ52gOM6tzuLZ5LoXdCWNfmoxq6d2ccDAYcBZ5csFi6kwcU(hi(CUG0hSfechmIpxi6kwcU(h4SrMlPW5nzHdNCoImWh91upEUIHahkAWOMdmiXduZLDi4PMaboS)44TCi4IAUSdbp1eiWvIiHAUSdbp1eiWz3zdgK4bQ5Yoe8utGaxXyjuZLDi4PMabUdJf8rp1CzhcEQjqGaxru)OxFzlCVv0Z9(h6TIzBKacgpt4EmoqcWfN3L1LxvvkbEMWDvPJJGa8S6wj3PxrIIQvQqACFRGaxGtzlLTUBPOHYgQMBrK2PJRJNjvPmHaja
this will show an icon for 5 seconds after you cast it. i used immolation aura to test it, but just find the spell id you want and replace that.
i have never made a weakaura like this before, but it was pretty simple! make one for each spell and you should be good for what you want!